The Hubble Deep Field: latest news
The link to the HDF South page has been added.
The ISO HDF web page
has been updated to include copies of the accepted papers (I-V),
tests of the reliability of sources, and other items of interest.
A search of the STScI library STEPsheet reveals the following
HDF Preprints and Publications. If yours is not listed here, please
send a copy to the STScI Librarian (Librarian, Space Telescope Science Institute,
3700 San Martin Drive, Baltimore, MD 21218).
Infrared followup obervations using the KPNO IRIM camera
are now available.
A new set of WFPC-2 mosaics
are available courtesy of Mark Dickinson and Richard Hook. The
World Coordinate System (WCS) keywords in the mosaics and in
the IRIM data have been updated to match the system defined in
Williams et al (1996, AJ, 112, 1335) based on radio interferometric
positions for several HDF sources. An iraf script
hdf_wcs_fix.cl is available to
updated the header information in the
version 2 drizzled images.
To make room for the mosaics, we have deleted
the version-1 HST WFPC images
from the archive disk. The v2 images
(still available) should be better for most purposes.
If (for some peculiar reason) you want the v1 images,
you may request a tape from
Plans are underway for a southern HDF. There is no specific date or
field yet for the observations.
Fields under consideration are being
searched for a suitable QSO for absorption line studies.
The topic for the 1997 STScI May Symposium will be the Hubble Deep Field.
Dates are still to be determined. Further details will be announced here,
through mailings, and on the STScI
meetings web page.
Redshifts from the DEEP project survey with Keck are now available.
Berkeley HDF group now has a web page, listing, among other
things redshifts for about 30 galaxies in the HDF and flanking
Redshifts from the Caltech and Hawaii Keck runs have been
added to the
Caltech web page.
Astrometry of the HDF flanking fields has been carried out
by the DEEP collaboration.
HDF version 3 has slowed considerably, mostly because it is
not a high priority given the modest expected gains in resolution
and S/N. The new target date is the end of the summer
A cautionary note on photometry. The
zeropoints listed for the HDF do not include a correction for
contamination, which progressively adds attenuation between
monthly decontaminations (warmups) of WFPC-2. As the HDF was
taken shortly after a DECON, this effect is less than 0.05 mag
for F300W, and significantly less for the redder filters.
The F300W correction will be posted here once it is computed.
A more serious concern is that the F300W exposures, which have
low backgrounds and low source count rates, are in a regime where
charge-transfer effects (CTE) could be significant. Measured
magnitudes of faint sources in the F300W band could be up to
0.2 mag fainter than true magnitudes, with the size of the
effect depending on row number. The effect is probably only a
few hundredths of a mag for the optical filters because of their
higher backgrounds. Laboratory tests and observations
in Cycle 6 are being planned to try to arrive at a calibration
of CTE as a function of row number, source count rate, background
level, the number of counts in the previous image, and the time
elapsed between images. Details of recent investigations of the
CTE and (and a similar, probably related photometric dependence
on exposure time) are posted on
WFPC-2 advisory page.
A TIFF format
image of the HDF + flanking fields, overlaid on
a KPNO 4-m image has been added, for use a finder chart.
CAUTION -- the frames in this image were aligned by eye.
Has anyone in the greater HDF community yet done a precise
registration of the HDF and flanking fields?
Added an update on
J, H, and K band observations from the
KPNO 4-m telescope.
It is now clear that we will miss the April 1 target date for the
version 3 release of the HDF data. We are in the midst of remaking
superdarks and superbiases, correcting at the same time for the
MgF faceplate glow. We are shooting for April 15.
There is a problem in the World Coordinate System (WCS) in the version
2 images. The v2 image headers have had a lot of stuff stripped out of
them that was in the v1 edition. 99% of that information was useless,
but two keywords pertaining to the WCS were not. The parameters
CTYPE1 and CTYPE2 should be set to 'RA---TAN' and 'DEC--TAN',
respectively (note the number of dashes in each entry!). Currently,
they are incorrectly set to 'PIXEL'.
The weight images in Version 2 give the inverse variance of the images in
counts per second per INPUT (WF- or PC-sized) pixel. However, when you
measure the noise in the drizzled images, you will be measuring it in counts
per second per OUTPUT pixel. The ratio of areas (and therefore counts)
between the input and output pixels is 6.25 in the WF and 1.31 in the PC. As a result
the standard deviation estimated from 1./sqrt(weight) must be divided by the
ratio of areas before comparison with the noise measured in the images.
Version 2 of the HDF data is now
available. The additional processing has resulted in roughly a 10%
improvement in S/N for the F450, F606, and F814W filters.
Information on image registration
and combination and on the
drizzle algortihm have been updated in preparation for the expected
release of Version 2 on 29 Feb 1996 (what would we have done were it
not a leap year?).
Proposals are now being solicited for ISO observations of the Hubble
Up-to-date information about the ISO mission and instruments can be
found on the ISO Homepage.
Detailed information about the HDF proposal opportunity is on the
same HomePage under the heading
"ISO and the Hubble Deep Field".
Version 2 is just about ready. Really. The final scattered light
subtraction is being done today.
Added a link to the University of Hawaii
HDF web page
provided by Len Cowie.
Version 2 of the data is running a bit behind. We had hoped to have
it ready Feb. 1, but it now looks like Feb. 8 is a better bet.
The masking of moving targets is almost complete. Then the frames will
be restacked, redrizzled, and will have scattered light subtracted.
The catalogs released on January 15 had an error in the x,y and
RA, DEC coordinates. They have been corrected and re-released
January 16. The new versions will be stored as FITS tables (*.fits)
rather than stsdas tables (*.tab), but may not propagate to the
ftp site until mid-day on January 16.
HDF web pages are installed, but many are incomplete and will
remain so until January 20th or so. If you have questions, contact
Copyright © 1997 The Association of Universities for
Research in Astronomy, Inc. All Rights Reserved.
Harry Ferguson firstname.lastname@example.org
Andy Fruchter email@example.com