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Subject: SPACE Digest V13 #203

SPACE Digest                                     Volume 13 : Issue 203

Today's Topics:
		      Some HST results and news

Administrivia:

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Date: 25 Feb 91 14:42:26 GMT
From: uvaarpa!haven!wam!cville.umd.edu!bunge@mcnc.org  (Robert David Bunge)
Subject: Some HST results and news

From: bunge@wam.umd.edu (Robert David Bunge)
Newsgroups: sci.astro,sci.space
Subject: Space Telescope early results
Summary: 
Followup-To: 
Distribution: world
Organization: University of Maryland at College Park
Keywords: 

                       Some early results from HST
 
 
(I wrote up the following after attending a Symposium and a Plenary Lecture
at the American Association for the Advancement of Science (AAAS) in
Washington, D.C. early last week.  In addition, some information was gleamed
from interviews afterwards.  I hope the more experienced science readers
of sci.astro/space will excuse the sometimes simple language - aimed at new
readers who may have not been around during previous discussions - Bob
Bunge)
 
----------------------
 
Hubble Space Telescope principle investigators presented a mixed review of
early science results from HST ranging from photographs showing detail
never imaged before, amazing new detailed spectra to two crippled
instruments, one perhaps even fatally.
 
In addition, investigators also showed as much concern over the
spacecraft's "jitter" as they did the flawed mirror.
 
Riccardo Giacconi, Director of the Space Telescope Science Institute
(STSI), said for the most part the space telescope is performing well
considering the mirror problem, but hinted that a jitter introduced by
shaking solar panels is more of a problem than previously thought.  The
jitter results when the solar panels expand and contract as they move in
and out of the shadow of the Earth.
 
While the flawed mirror has affected almost all science programs, in many
cases it can be corrected for during either the planning stages or during
data reduction.
 
"Even with ST in crippled condition, we can still do science, but ST can't see
galaxy formation.  Nature has been very kind to us even through we have a
crippled telescope," Giacconi said.  Seeing the early period of galaxy
formation had been a key area of research that HST promised to probe.
 
However, attempts at correcting the jitter by adjusting the telescope's
reaction wheels has not been completely successful.  This has affected the
telescope's ability to place starlight into the High Speed Photometers
(HSP) tiny apertures along with planned astrometry to be done with the Fine
Guidance Sensors.  
 
Giacconi also commented the war in the gulf has affected them somewhat
because of heavy Department of Defense usage of communication satellites
(TDRSS).  Apparently this at times this as slowed down the amount of data
received.
 
Eric Chaisson of STSI outlined plans to correct the jitter and the flawed
optics.  He explained aside from corrective optics in the new Wide Field
Planetary Camera (WF/PC, pronounced "wiff-pick") the Corrective Optics
Space Telescope Axial Replacement (COSTAR) would replace the HSP and swing
corrective optics using mirrors over the apertures of the remaining
instruments.  He said they are expecting to receive the go ahead on COSTAR
in the form of a recommendation from a group of astronomers in late
February.
 
Chaisson said the jitter was pronounced at two frequencies, 1/6th and 1/10
Hz, and while software has pretty much corrected the 1/6 Hz jitter, the
1/10 Hz jitter was too fast for the reaction wheels to correct and would
most likely remain a problem until the telescope's solar panels are
replaced.
 
He also added they have a shuttle flight scheduled for late (penciled in for
November) 1993 to try three repairs.  The first is to replace the current
WF/PC with WF/PC II.  The new camera will have newer filters and CCD
detectors.  The second goal will be to install new solar panels that will
eliminate the cause of the jitter.  The third would be to install COSTAR.  To
do all three of these tasks will require three complete days of astronaut
EVA, more than ever done during any previous shuttle flight.  
 
"We have addressed these concerns to the shuttle people and they tell us
it is possible, so we are planning to do it," he said.  It was not said if they
will also try to replace a broken gyro during this flight.  However, the news
of COSTAR and its corrective optics hasn't been good news for everyone.
 
In a pessimistic press release handed out before the symposia, HSP
principal investigator Robert C. Bless of the University of Wisconsin-
Madison, reported they were "dead in the water" because of the telescopes
inability to place the center section of a stellar image on any of a number
of tiny apertures in HSP.  This bad news has been aggravated by the news
that the HSP will be replaced by COSTAR just as the jitter problem is fixed.
 
But Bless's co-researcher Jeffery Percival was more upbeat about the
status of HSP.  Even though he didn't have any science results to present,
he said a recent software fix for the jitter showed some promise and they
have been promised priority scheduling before the 1993 repair flight if HSP
regains some usefulness.
 
Chaisson added that the HSP was the most under subscribed instrument and
was scheduled for early replacement even before the affects of the jitter
on HSP became known.
 
F. Duccio Macchetto of the European Space Agency reported on early
results obtained with the Faint Object Camera (FOC).  He showed slides of
Pluto and Charon, the "Einstein Cross" gravitational lens and the ring
around supernova 1987a.  He reported that the FOC is operating flawlessly
and researchers have been happy with results in light of the flawed optics.
 
Researchers from both the Goddard High Resolution Spectrograph (GHRS) and
the Faint Object Spectrograph (FOS) reported good results even with the
optics and presented baseline observations designed to allow the
scientific community to gauge the affect of the flawed optics on any future
science programs.
 
John Brandt of the University of Colorado at Boulder reported on spectra
of red giant Alpha Tauri, blue supergiant Melnick 42 and Xi Persei.  He said
while the Large Science Aperture in GHRS had suffered a loss of about 50
percent of expected resolution, the Small Science Aperture was mostly
unaffected.  In both cases, the spread out stellar images mean longer
exposures are required and targets must not be close to other objects. 
With each object he displayed GHRS spectra against ground based spectra
to show that ST was resolving many new - 24 in the case of Alpha Tauri
across a 50 angstrom band, - lines.
 
Richard Harms of Applied Research Corp. in Landover MD reported similar
results with the FOS.  He said the instrument required exposures three to
four times longer because of the flawed optics.  While early results based
on spectra on Seyfert galaxy NGC 1068 and globular cluster M-14 have been
promising, the smallest apertures of the instrument have been rendered
useless by the jitter because the light from an object cannot be centered
on the apertures for any length of time.
 
Laurence W. Fredrick of the University of Virginia reported on science
programs using the Fine Guidance Sensors (FGS).  He said for the most part
astrometry programs are on "hold" because of the jitter and the telescopes
current state of collimation.
 
Apparently, the spherical aberration has affected the (wave front) sensors
that provide information needed to collimate the telescope's optics.  In
turn, this has affected the FGS because they are sensitive to asymmetrical
aberration such as coma and astigmatism introduced because of the bad
collimation.  It is hoped that future movements of the secondary mirror can
be made to correct these problems.
 
Fredrick did show results of some science done with the FGS in the form of
more accurate measurements of the double star ADS 11300.  Researchers
were able to remove error introduced by the jitter to come up with the
most accurate information on this star system yet.
 
James Westphal of Caltech and the principal investigator for the Wide Field
Planetary Camera showed a series of images of Saturn, before and after
the white spot, M-42, NGC 7457 and a pre-release blue light image of Eta
Carina.  The image of Eta Carina clearly showed huge, complex loops of
matter blown off the star.  He said a color image of the star will be
released in the near future.  
 
Westphal also said a team who took images of Mars with the planetary
camera when it was near opposition will also release color images in coming
weeks.  Another up coming WF/PC release will be a new "movie" using some of
the 600 images taken of Saturn while observing the white spot last
November.
 
Westphal said they expect to start taking images of Jupiter within the next
three weeks and they will also target Saturn starting on the 15th of March
if ground based observers report interesting activities following the
ringed planets coming out from behind the Sun.  
 
Later, when asked why it took more than a month to get ST pointed at Saturn
after the discovery of the white spot, Westphal said they had approached
ST's first target of opportunity with caution and some procedures had to
be worked out.  He said currently ST can be pointed to any object within two
days of a decision being made to do so.  
Qf~? 
He also said if the optics had been flawless, the jitter would have affected
the telescope almost as much as the bad optics.  He said some people in the
control room during the night of "first light" had suspected the spherical
aberration long before it was officially announced. 
 
Finally, Robert O'Dell of Rice University reported on what might be the
first case of results from ground based follow-up research based on HST
science.
 
Using an image of M-42 taken with the WF/PC, (see page 32 of the February
_ASTRONOMY_ magazine) spectra taken with a ground based telescope had
shown what was believed to have been a jet of gas shooting from a young
hot star (middle far right side of image just above the horizonal line in the
ASTRONOMY image) is really a ionization front near the star.  But, a
"elephant trunk" shaped bright region nearby (upper far right in ASTRONOMY
image) is a jet from a star.  O'Dell said these objects are described wrong
in an up coming issue of ApJ letters.
 
 
Bob Bunge
bunge@wam.umd.edu


From: bunge@wam.umd.edu (Robert David Bunge)
Newsgroups: sci.astro,sci.space
Subject: HST early results
Summary: 
Followup-To: 
Distribution: world
Organization: University of Maryland at College Park
Keywords: 

From: bunge@wam.umd.edu (Robert David Bunge)
Newsgroups: sci.astro,sci.space
Subject: Space Telescope early results
Summary: 
Followup-To: 
Distribution: world
Organization: University of Maryland at College Park
Keywords: 

                       Some early results from HST
 
 
(I wrote up the following after attending a Symposium and a Plenary Lecture
at the American Association for the Advancement of Science (AAAS) in
Washington, D.C. early last week.  In addition, some information was gleamed
from interviews afterwards.  I hope the more experienced science readers
of sci.astro/space will excuse the sometimes simple language - aimed at new
readers who may have not been around during previous discussions - Bob
Bunge)
 
----------------------
 
Hubble Space Telescope principle investigators presented a mixed review of
early science results from HST ranging from photographs showing detail
never imaged before, amazing new detailed spectra to two crippled
instruments, one perhaps even fatally.
 
In addition, investigators also showed as much concern over the
spacecraft's "jitter" as they did the flawed mirror.
 
Riccardo Giacconi, Director of the Space Telescope Science Institute
(STSI), said for the most part the space telescope is performing well
considering the mirror problem, but hinted that a jitter introduced by
shaking solar panels is more of a problem than previously thought.  The
jitter results when the solar panels expand and contract as they move in
and out of the shadow of the Earth.
 
While the flawed mirror has affected almost all science programs, in many
cases it can be corrected for during either the planning stages or during
data reduction.
 
"Even with ST in crippled condition, we can still do science, but ST can't see
galaxy formation.  Nature has been very kind to us even through we have a
crippled telescope," Giacconi said.  Seeing the early period of galaxy
formation had been a key area of research that HST promised to probe.
 
However, attempts at correcting the jitter by adjusting the telescope's
reaction wheels has not been completely successful.  This has affected the
telescope's ability to place starlight into the High Speed Photometers
(HSP) tiny apertures along with planned astrometry to be done with the Fine
Guidance Sensors.  
 
Giacconi also commented the war in the gulf has affected them somewhat
because of heavy Department of Defense usage of communication satellites
(TDRSS).  Apparently this at times this as slowed down the amount of data
received.
 
Eric Chaisson of STSI outlined plans to correct the jitter and the flawed
optics.  He explained aside from corrective optics in the new Wide Field
Planetary Camera (WF/PC, pronounced "wiff-pick") the Corrective Optics
Space Telescope Axial Replacement (COSTAR) would replace the HSP and swing
corrective optics using mirrors over the apertures of the remaining
instruments.  He said they are expecting to receive the go ahead on COSTAR
in the form of a recommendation from a group of astronomers in late
February.
 
Chaisson said the jitter was pronounced at two frequencies, 1/6th and 1/10
Hz, and while software has pretty much corrected the 1/6 Hz jitter, the
1/10 Hz jitter was too fast for the reaction wheels to correct and would
most likely remain a problem until the telescope's solar panels are
replaced.
 
He also added they have a shuttle flight scheduled for late (penciled in for
November) 1993 to try three repairs.  The first is to replace the current
WF/PC with WF/PC II.  The new camera will have newer filters and CCD
detectors.  The second goal will be to install new solar panels that will
eliminate the cause of the jitter.  The third would be to install COSTAR.  To
do all three of these tasks will require three complete days of astronaut
EVA, more than ever done during any previous shuttle flight.  
 
"We have addressed these concerns to the shuttle people and they tell us
it is possible, so we are planning to do it," he said.  It was not said if they
will also try to replace a broken gyro during this flight.  However, the news
of COSTAR and its corrective optics hasn't been good news for everyone.
 
In a pessimistic press release handed out before the symposia, HSP
principal investigator Robert C. Bless of the University of Wisconsin-
Madison, reported they were "dead in the water" because of the telescopes
inability to place the center section of a stellar image on any of a number
of tiny apertures in HSP.  This bad news has been aggravated by the news
that the HSP will be replaced by COSTAR just as the jitter problem is fixed.
 
But Bless's co-researcher Jeffery Percival was more upbeat about the
status of HSP.  Even though he didn't have any science results to present,
he said a recent software fix for the jitter showed some promise and they
have been promised priority scheduling before the 1993 repair flight if HSP
regains some usefulness.
 
Chaisson added that the HSP was the most under subscribed instrument and
was scheduled for early replacement even before the affects of the jitter
on HSP became known.
 
F. Duccio Macchetto of the European Space Agency reported on early
results obtained with the Faint Object Camera (FOC).  He showed slides of
Pluto and Charon, the "Einstein Cross" gravitational lens and the ring
around supernova 1987a.  He reported that the FOC is operating flawlessly
and researchers have been happy with results in light of the flawed optics.
 
Researchers from both the Goddard High Resolution Spectrograph (GHRS) and
the Faint Object Spectrograph (FOS) reported good results even with the
optics and presented baseline observations designed to allow the
scientific community to gauge the affect of the flawed optics on any future
science programs.
 
John Brandt of the University of Colorado at Boulder reported on spectra
of red giant Alpha Tauri, blue supergiant Melnick 42 and Xi Persei.  He said
while the Large Science Aperture in GHRS had suffered a loss of about 50
percent of expected resolution, the Small Science Aperture was mostly
unaffected.  In both cases, the spread out stellar images mean longer
exposures are required and targets must not be close to other objects. 
With each object he displayed GHRS spectra against ground based spectra
to show that ST was resolving many new - 24 in the case of Alpha Tauri
across a 50 angstrom band, - lines.
 
Richard Harms of Applied Research Corp. in Landover MD reported similar
results with the FOS.  He said the instrument required exposures three to
four times longer because of the flawed optics.  While early results based
on spectra on Seyfert galaxy NGC 1068 and globular cluster M-14 have been
promising, the smallest apertures of the instrument have been rendered
useless by the jitter because the light from an object cannot be centered
on the apertures for any length of time.
 
Laurence W. Fredrick of the University of Virginia reported on science
programs using the Fine Guidance Sensors (FGS).  He said for the most part
astrometry programs are on "hold" because of the jitter and the telescopes
current state of collimation.
 
Apparently, the spherical aberration has affected the (wave front) sensors
that provide information needed to collimate the telescope's optics.  In
turn, this has affected the FGS because they are sensitive to asymmetrical
aberration such as coma and astigmatism introduced because of the bad
collimation.  It is hoped that future movements of the secondary mirror can
be made to correct these problems.
 
Fredrick did show results of some science done with the FGS in the form of
more accurate measurements of the double star ADS 11300.  Researchers
were able to remove error introduced by the jitter to come up with the
most accurate information on this star system yet.
 
James Westphal of Caltech and the principal investigator for the Wide Field
Planetary Camera showed a series of images of Saturn, before and after
the white spot, M-42, NGC 7457 and a pre-release blue light image of Eta
Carina.  The image of Eta Carina clearly showed huge, complex loops of
matter blown off the star.  He said a color image of the star will be
released in the near future.  
 
Westphal also said a team who took images of Mars with the planetary
camera when it was near opposition will also release color images in coming
weeks.  Another up coming WF/PC release will be a new "movie" using some of
the 600 images taken of Saturn while observing the white spot last
November.
 
Westphal said they expect to start taking images of Jupiter within the next
three weeks and they will also target Saturn starting on the 15th of March
if ground based observers report interesting activities following the
ringed planets coming out from behind the Sun.  
 
Later, when asked why it took more than a month to get ST pointed at Saturn
after the discovery of the white spot, Westphal said they had approached
ST's first target of opportunity with caution and some procedures had to
be worked out.  He said currently ST can be pointed to any object within two
days of a decision being made to do so.  
Qf~? 
He also said if the optics had been flawless, the jitter would have affected
the telescope almost as much as the bad optics.  He said some people in the
control room during the night of "first light" had suspected the spherical
aberration long before it was officially announced. 
 
Finally, Robert O'Dell of Rice University reported on what might be the
first case of results from ground based follow-up research based on HST
science.
 
Using an image of M-42 taken with the WF/PC, (see page 32 of the February
_ASTRONOMY_ magazine) spectra taken with a ground based telescope had
shown what was believed to have been a jet of gas shooting from a young
hot star (middle far right side of image just above the horizonal line in the
ASTRONOMY image) is really a ionization front near the star.  But, a
"elephant trunk" shaped bright region nearby (upper far right in ASTRONOMY
image) is a jet from a star.  O'Dell said these objects are described wrong
in an up coming issue of ApJ letters.
 
 
Bob Bunge
bunge@wam.umd.edu


From: bunge@wam.umd.edu (Robert David Bunge)
Newsgroups: sci.astro,sci.space
Subject: HST early results
Summary: 
Followup-To: 
Distribution: world
Organization: University of Maryland at College Park
Keywords: 

From: bunge@wam.umd.edu (Robert David Bunge)
Newsgroups: sci.astro,sci.space
Subject: Space Telescope early results
Summary: 
Followup-To: 
Distribution: world
Organization: University of Maryland at College Park
Keywords: 

                       Some early results from HST
 
 
(I wrote up the following after attending a Symposium and a Plenary Lecture
at the American Association for the Advancement of Science (AAAS) in
Washington, D.C. early last week.  In addition, some information was gleamed
from interviews afterwards.  I hope the more experienced science readers
of sci.astro/space will excuse the sometimes simple language - aimed at new
readers who may have not been around during previous discussions - Bob
Bunge)
 
----------------------
 
Hubble Space Telescope principle investigators presented a mixed review of
early science results from HST ranging from photographs showing detail
never imaged before, amazing new detailed spectra to two crippled
instruments, one perhaps even fatally.
 
In addition, investigators also showed as much concern over the
spacecraft's "jitter" as they did the flawed mirror.
 
Riccardo Giacconi, Director of the Space Telescope Science Institute
(STSI), said for the most part the space telescope is performing well
considering the mirror problem, but hinted that a jitter introduced by
shaking solar panels is more of a problem than previously thought.  The
jitter results when the solar panels expand and contract as they move in
and out of the shadow of the Earth.
 
While the flawed mirror has affected almost all science programs, in many
cases it can be corrected for during either the planning stages or during
data reduction.
 
"Even with ST in crippled condition, we can still do science, but ST can't see
galaxy formation.  Nature has been very kind to us even through we have a
crippled telescope," Giacconi said.  Seeing the early period of galaxy
formation had been a key area of research that HST promised to probe.
 
However, attempts at correcting the jitter by adjusting the telescope's
reaction wheels has not been completely successful.  This has affected the
telescope's ability to place starlight into the High Speed Photometers
(HSP) tiny apertures along with planned astrometry to be done with the Fine
Guidance Sensors.  
 
Giacconi also commented the war in the gulf has affected them somewhat
because of heavy Department of Defense usage of communication satellites
(TDRSS).  Apparently this at times this as slowed down the amount of data
received.
 
Eric Chaisson of STSI outlined plans to correct the jitter and the flawed
optics.  He explained aside from corrective optics in the new Wide Field
Planetary Camera (WF/PC, pronounced "wiff-pick") the Corrective Optics
Space Telescope Axial Replacement (COSTAR) would replace the HSP and swing
corrective optics using mirrors over the apertures of the remaining
instruments.  He said they are expecting to receive the go ahead on COSTAR
in the form of a recommendation from a group of astronomers in late
February.
 
Chaisson said the jitter was pronounced at two frequencies, 1/6th and 1/10
Hz, and while software has pretty much corrected the 1/6 Hz jitter, the
1/10 Hz jitter was too fast for the reaction wheels to correct and would
most likely remain a problem until the telescope's solar panels are
replaced.
 
He also added they have a shuttle flight scheduled for late (penciled in for
November) 1993 to try three repairs.  The first is to replace the current
WF/PC with WF/PC II.  The new camera will have newer filters and CCD
detectors.  The second goal will be to install new solar panels that will
eliminate the cause of the jitter.  The third would be to install COSTAR.  To
do all three of these tasks will require three complete days of astronaut
EVA, more than ever done during any previous shuttle flight.  
 
"We have addressed these concerns to the shuttle people and they tell us
it is possible, so we are planning to do it," he said.  It was not said if they
will also try to replace a broken gyro during this flight.  However, the news
of COSTAR and its corrective optics hasn't been good news for everyone.
 
In a pessimistic press release handed out before the symposia, HSP
principal investigator Robert C. Bless of the University of Wisconsin-
Madison, reported they were "dead in the water" because of the telescopes
inability to place the center section of a stellar image on any of a number
of tiny apertures in HSP.  This bad news has been aggravated by the news
that the HSP will be replaced by COSTAR just as the jitter problem is fixed.
 
But Bless's co-researcher Jeffery Percival was more upbeat about the
status of HSP.  Even though he didn't have any science results to present,
he said a recent software fix for the jitter showed some promise and they
have been promised priority scheduling before the 1993 repair flight if HSP
regains some usefulness.
 
Chaisson added that the HSP was the most under subscribed instrument and
was scheduled for early replacement even before the affects of the jitter
on HSP became known.
 
F. Duccio Macchetto of the European Space Agency reported on early
results obtained with the Faint Object Camera (FOC).  He showed slides of
Pluto and Charon, the "Einstein Cross" gravitational lens and the ring
around supernova 1987a.  He reported that the FOC is operating flawlessly
and researchers have been happy with results in light of the flawed optics.
 
Researchers from both the Goddard High Resolution Spectrograph (GHRS) and
the Faint Object Spectrograph (FOS) reported good results even with the
optics and presented baseline observations designed to allow the
scientific community to gauge the affect of the flawed optics on any future
science programs.
 
John Brandt of the University of Colorado at Boulder reported on spectra
of red giant Alpha Tauri, blue supergiant Melnick 42 and Xi Persei.  He said
while the Large Science Aperture in GHRS had suffered a loss of about 50
percent of expected resolution, the Small Science Aperture was mostly
unaffected.  In both cases, the spread out stellar images mean longer
exposures are required and targets must not be close to other objects. 
With each object he displayed GHRS spectra against ground based spectra
to show that ST was resolving many new - 24 in the case of Alpha Tauri
across a 50 angstrom band, - lines.
 
Richard Harms of Applied Research Corp. in Landover MD reported similar
results with the FOS.  He said the instrument required exposures three to
four times longer because of the flawed optics.  While early results based
on spectra on Seyfert galaxy NGC 1068 and globular cluster M-14 have been
promising, the smallest apertures of the instrument have been rendered
useless by the jitter because the light from an object cannot be centered
on the apertures for any length of time.
 
Laurence W. Fredrick of the University of Virginia reported on science
programs using the Fine Guidance Sensors (FGS).  He said for the most part
astrometry programs are on "hold" because of the jitter and the telescopes
current state of collimation.
 
Apparently, the spherical aberration has affected the (wave front) sensors
that provide information needed to collimate the telescope's optics.  In
turn, this has affected the FGS because they are sensitive to asymmetrical
aberration such as coma and astigmatism introduced because of the bad
collimation.  It is hoped that future movements of the secondary mirror can
be made to correct these problems.
 
Fredrick did show results of some science done with the FGS in the form of
more accurate measurements of the double star ADS 11300.  Researchers
were able to remove error introduced by the jitter to come up with the
most accurate information on this star system yet.
 
James Westphal of Caltech and the principal investigator for the Wide Field
Planetary Camera showed a series of images of Saturn, before and after
the white spot, M-42, NGC 7457 and a pre-release blue light image of Eta
Carina.  The image of Eta Carina clearly showed huge, complex loops of
matter blown off the star.  He said a color image of the star will be
released in the near future.  
 
Westphal also said a team who took images of Mars with the planetary
camera when it was near opposition will also release color images in coming
weeks.  Another up coming WF/PC release will be a new "movie" using some of
the 600 images taken of Saturn while observing the white spot last
November.
 
Westphal said they expect to start taking images of Jupiter within the next
three weeks and they will also target Saturn starting on the 15th of March
if ground based observers report interesting activities following the
ringed planets coming out from behind the Sun.  
 
Later, when asked why it took more than a month to get ST pointed at Saturn
after the discovery of the white spot, Westphal said they had approached
ST's first target of opportunity with caution and some procedures had to
be worked out.  He said currently ST can be pointed to any object within two
days of a decision being made to do so.  
Qf~? 
He also said if the optics had been flawless, the jitter would have affected
the telescope almost as much as the bad optics.  He said some people in the
control room during the night of "first light" had suspected the spherical
aberration long before it was officially announced. 
 
Finally, Robert O'Dell of Rice University reported on what might be the
first case of results from ground based follow-up research based on HST
science.
 
Using an image of M-42 taken with the WF/PC, (see page 32 of the February
_ASTRONOMY_ magazine) spectra taken with a ground based telescope had
shown what was believed to have been a jet of gas shooting from a young
hot star (middle far right side of image just above the horizonal line in the
ASTRONOMY image) is really a ionization front near the star.  But, a
"elephant trunk" shaped bright region nearby (upper far right in ASTRONOMY
image) is a jet from a star.  O'Dell said these objects are described wrong
in an up coming issue of ApJ letters.
 
 
Bob Bunge
bunge@wam.umd.edu


From: bunge@wam.umd.edu (Robert David Bunge)
Newsgroups: sci.astro,sci.space
Subject: HST early results
Summary: 
Followup-To: 
Distribution: world
Organization: University of Maryland at College Park
Keywords: 

From: bunge@wam.umd.edu (Robert David Bunge)
Newsgroups: sci.astro,sci.space
Subject: Space Telescope early results
Summary: 
Followup-To: 
Distribution: world
Organization: University of Maryland at College Park
Keywords: 

                       Some early results from HST
 
 
(I wrote up the following after attending a Symposium and a Plenary Lecture
at the American Association for the Advancement of Science (AAAS) in
Washington, D.C. early last week.  In addition, some information was gleamed
from interviews afterwards.  I hope the more experienced science readers
of sci.astro/space will excuse the sometimes simple language - aimed at new
readers who may have not been around during previous discussions - Bob
Bunge)
 
----------------------
 
Hubble Space Telescope principle investigators presented a mixed review of
early science results from HST ranging from photographs showing detail
never imaged before, amazing new detailed spectra to two crippled
instruments, one perhaps even fatally.
 
In addition, investigators also showed as much concern over the
spacecraft's "jitter" as they did the flawed mirror.
 
Riccardo Giacconi, Director of the Space Telescope Science Institute
(STSI), said for the most part the space telescope is performing well
considering the mirror problem, but hinted that a jitter introduced by
shaking solar panels is more of a problem than previously thought.  The
jitter results when the solar panels expand and contract as they move in
and out of the shadow of the Earth.
 
While the flawed mirror has affected almost all science programs, in many
cases it can be corrected for during either the planning stages or during
data reduction.
 
"Even with ST in crippled condition, we can still do science, but ST can't see
galaxy formation.  Nature has been very kind to us even through we have a
crippled telescope," Giacconi said.  Seeing the early period of galaxy
formation had been a key area of research that HST promised to probe.
 
However, attempts at correcting the jitter by adjusting the telescope's
reaction wheels has not been completely successful.  This has affected the
telescope's ability to place starlight into the High Speed Photometers
(HSP) tiny apertures along with planned astrometry to be done with the Fine
Guidance Sensors.  
 
Giacconi also commented the war in the gulf has affected them somewhat
because of heavy Department of Defense usage of communication satellites
(TDRSS).  Apparently this at times this as slowed down the amount of data
received.
 
Eric Chaisson of STSI outlined plans to correct the jitter and the flawed
optics.  He explained aside from corrective optics in the new Wide Field
Planetary Camera (WF/PC, pronounced "wiff-pick") the Corrective Optics
Space Telescope Axial Replacement (COSTAR) would replace the HSP and swing
corrective optics using mirrors over the apertures of the remaining
instruments.  He said they are expecting to receive the go ahead on COSTAR
in the form of a recommendation from a group of astronomers in late
February.
 
Chaisson said the jitter was pronounced at two frequencies, 1/6th and 1/10
Hz, and while software has pretty much corrected the 1/6 Hz jitter, the
1/10 Hz jitter was too fast for the reaction wheels to correct and would
most likely remain a problem until the telescope's solar panels are
replaced.
 
He also added they have a shuttle flight scheduled for late (penciled in for
November) 1993 to try three repairs.  The first is to replace the current
WF/PC with WF/PC II.  The new camera will have newer filters and CCD
detectors.  The second goal will be to install new solar panels that will
eliminate the cause of the jitter.  The third would be to install COSTAR.  To
do all three of these tasks will require three complete days of astronaut
EVA, more than ever done during any previous shuttle flight.  
 
"We have addressed these concerns to the shuttle people and they tell us
it is possible, so we are planning to do it," he said.  It was not said if they
will also try to replace a broken gyro during this flight.  However, the news
of COSTAR and its corrective optics hasn't been good news for everyone.
 
In a pessimistic press release handed out before the symposia, HSP
principal investigator Robert C. Bless of the University of Wisconsin-
Madison, reported they were "dead in the water" because of the telescopes
inability to place the center section of a stellar image on any of a number
of tiny apertures in HSP.  This bad news has been aggravated by the news
that the HSP will be replaced by COSTAR just as the jitter problem is fixed.
 
But Bless's co-researcher Jeffery Percival was more upbeat about the
status of HSP.  Even though he didn't have any science results to present,
he said a recent software fix for the jitter showed some promise and they
have been promised priority scheduling before the 1993 repair flight if HSP
regains some usefulness.
 
Chaisson added that the HSP was the most under subscribed instrument and
was scheduled for early replacement even before the affects of the jitter
on HSP became known.
 
F. Duccio Macchetto of the European Space Agency reported on early
results obtained with the Faint Object Camera (FOC).  He showed slides of
Pluto and Charon, the "Einstein Cross" gravitational lens and the ring
around supernova 1987a.  He reported that the FOC is operating flawlessly
and researchers have been happy with results in light of the flawed optics.
 
Researchers from both the Goddard High Resolution Spectrograph (GHRS) and
the Faint Object Spectrograph (FOS) reported good results even with the
optics and presented baseline observations designed to allow the
scientific community to gauge the affect of the flawed optics on any future
science programs.
 
John Brandt of the University of Colorado at Boulder reported on spectra
of red giant Alpha Tauri, blue supergiant Melnick 42 and Xi Persei.  He said
while the Large Science Aperture in GHRS had suffered a loss of about 50
percent of expected resolution, the Small Science Aperture was mostly
unaffected.  In both cases, the spread out stellar images mean longer
exposures are required and targets must not be close to other objects. 
With each object he displayed GHRS spectra against ground based spectra
to show that ST was resolving many new - 24 in the case of Alpha Tauri
across a 50 angstrom band, - lines.
 
Richard Harms of Applied Research Corp. in Landover MD reported similar
results with the FOS.  He said the instrument required exposures three to
four times longer because of the flawed optics.  While early results based
on spectra on Seyfert galaxy NGC 1068 and globular cluster M-14 have been
promising, the smallest apertures of the instrument have been rendered
useless by the jitter because the light from an object cannot be centered
on the apertures for any length of time.
 
Laurence W. Fredrick of the University of Virginia reported on science
programs using the Fine Guidance Sensors (FGS).  He said for the most part
astrometry programs are on "hold" because of the jitter and the telescopes
current state of collimation.
 
Apparently, the spherical aberration has affected the (wave front) sensors
that provide information needed to collimate the telescope's optics.  In
turn, this has affected the FGS because they are sensitive to asymmetrical
aberration such as coma and astigmatism introduced because of the bad
collimation.  It is hoped that future movements of the secondary mirror can
be made to correct these problems.
 
Fredrick did show results of some science done with the FGS in the form of
more accurate measurements of the double star ADS 11300.  Researchers
were able to remove error introduced by the jitter to come up with the
most accurate information on this star system yet.
 
James Westphal of Caltech and the principal investigator for the Wide Field
Planetary Camera showed a series of images of Saturn, before and after
the white spot, M-42, NGC 7457 and a pre-release blue light image of Eta
Carina.  The image of Eta Carina clearly showed huge, complex loops of
matter blown off the star.  He said a color image of the star will be
released in the near future.  
 
Westphal also said a team who took images of Mars with the planetary
camera when it was near opposition will also release color images in coming
weeks.  Another up coming WF/PC release will be a new "movie" using some of
the 600 images taken of Saturn while observing the white spot last
November.
 
Westphal said they expect to start taking images of Jupiter within the next
three weeks and they will also target Saturn starting on the 15th of March
if ground based observers report interesting activities following the
ringed planets coming out from behind the Sun.  
 
Later, when asked why it took more than a month to get ST pointed at Saturn
after the discovery of the white spot, Westphal said they had approached
ST's first target of opportunity with caution and some procedures had to
be worked out.  He said currently ST can be pointed to any object within two
days of a decision being made to do so.  
Qf~? 
He also said if the optics had been flawless, the jitter would have affected
the telescope almost as much as the bad optics.  He said some people in the
control room during the night of "first light" had suspected the spherical
aberration long before it was officially announced. 
 
Finally, Robert O'Dell of Rice University reported on what might be the
first case of results from ground based follow-up research based on HST
science.
 
Using an image of M-42 taken with the WF/PC, (see page 32 of the February
_ASTRONOMY_ magazine) spectra taken with a ground based telescope had
shown what was believed to have been a jet of gas shooting from a young
hot star (middle far right side of image just above the horizonal line in the
ASTRONOMY image) is really a ionization front near the star.  But, a
"elephant trunk" shaped bright region nearby (upper far right in ASTRONOMY
image) is a jet from a star.  O'Dell said these objects are described wrong
in an up coming issue of ApJ letters.
 
 
Bob Bunge
bunge@wam.umd.edu

------------------------------

End of SPACE Digest V13 #203
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