The SM3a Early Release Observations
Introduction
In mid-January 2000, a series of Early Release Obervations (EROs) were
taken as part of the Hubble Space Telescope Servicing Mission 3a Orbital
Verification. The purpose of these observations
was to provide the public
and the astronomical community
with graphic proof that HST was again working as intended. Two
targets were chosen, NGC 2392, the "Eskimo" planetary nebula,
and Abell 2218, a galaxy cluster at z=0.17 known for the rich
assembly of lensed arcs about its core. These objects were
chosen both for their visual beauty and their scientific import.
The press releases associated with these observations can be reached
by clicking on the images above.
Information on our processing
techniques and on how to retrieve the processed images is presented below.
NGC 2392
NGC 2392 was observed in four narrow band
filters using the Wide Field and Planetary
Camera 2 (WFPC2) on HST. The four filters were: F469N (HeII), F502N ([O III]),
F656N (H alpha), and F658N ([N II]). Four exposures were taken
in each filter
with total exposure times of
1400, 400, 400, and 1400 s respectively. The exposures in each filter
were taken using the standard four-point dither offsets for WFPC2.
The images were combined using the "Drizzle" program. The raw data and processed individual
images can be obtained from the
HST archive. The drizzled, combined
images used to create the press release can be retrieved
here. Users wishing to do their own processing
on the individual images may nonetheless find the README file in the drizzled image
directory useful.
Abell 2218
Abell 2218 was observed in three different filters, F450W (B), F606W
(V/R), and F814W (I). A combination of small and large dithers was
used during these observations to allow a seamless joining of the images
from the different WFPC2 chips. All individual exposures were
1000s long. The total exposure times were F450W, 12000s; F606W, 10,000s;
and F814W, 12000s. As in the case of the NGC 2392 data, the raw data
as well as processed individual
images can be retrieved from the HST
archive. The drizzled mosaics used for the press release are available
here. Users wishing to do their own processing may
nonetheless find the README file in the drizzled image
directory useful.
For more information on these images
you can contact Andy
Fruchter (STScI) or any member of the
ERO
Team.
