The ST-ECF is managing the processing of ACS HRC Parallels. The two pairs of overlapping fields both fall mainly in the GOODS-South field.
|RA (2000.0)||03 32 54||03 32 31|
|DEC (2000.0)||-27 49 17||-27 50 49|
|T(F220W)||62 ks||52 ks|
|T(F555W)||63 ks||57 ks|
|T(F892N)||169 ks||135 ks|
|T(G800L)||164 ks||135 ks|
ACS/HRC Scientific Rationale:
The ACS High Resolution Channel (HRC) offers the possibility
to obtain auto-parallels when the WFC is prime. Since the
Wide Field Channel (WFC) and the HRC share the same filter
wheels, the filter in use by WFC dictates the HRC filter.
For the HUDF observations HRC auto-parallels have been
obtained with the F220W, F555W and F892N filters and the
G800L grism. The scientific aim is to obtain complementary deep
images at a spatial resolution about twice that of the WFC
over a smaller field. The pixel size is 0.027arcsec so the
sensitivity to compact sources is higher than for WFC. The
F555W images will provide a deep V band image; the F220W although
not very sensitive will provide a UV colour which may be interesting
for the UV morphology of nearby galaxies and low-moderate redshift
objects (z~<2). The F892N filter is narrow (150A) but is of interest
for detecting emission line objects in a narrow range, such as
[O II] emitters 1.37
Approximate coordinates for the 2 pairs of ACS HRC parallels are:
Epoch 1, ORIENT 310 RA (J2000)= 03 32 54.4 DEC (J2000)= -27 49 07.3 ~center Epoch 1, ORIENT 314 RA (J2000)= 03 32 53.8 DEC (J2000)= -27 49 21.8 ~center Epoch 2, ORIENT 40 RA (J2000)= 03 32 31.6 DEC (J2000)= -27 50 52.1 ~center Epoch 2, ORIENT 44 RA (J2000)= 03 32 30.5 DEC (J2000)= -27 50 45.0 ~center
ACS/HRC autoparallel filters are automatically determined by the ACS/WFC primary filter in use. The UDF filter pairings are below:
The limiting magnitude estimates below were calculated using the ACS ETC. As specified for the ACS/WFC exposures, the calculations are for a S/N of 10 within a 0.2 sq arcsec aperture (15x15 HRC pixels) and average zodiac and earthshine.
Limiting AB magnitudes for S/N = 10 in 15x15 pixels aperture.
|Orient 310||Orient 314||Overlap|
The limiting magnitude estimates in the above table should be considered crude guidelines only. Estimates of limiting magnitudes are complicated by the uneven exposures in different parts of the images, different angular sizes of the objects etc. The faintest objects detected in the F555W frames in the Epoch-1 and Epoch-2 data have AB magnitudes of 28.5 and 28.3, respectively. Histograms of the magnitude distributions of objects in the two HRC fields show a rapid decline below ABmag(F555W) = 28, suggesting that significant incompleteness sets in around this limit.
PeopleThe Hubble Ultra Deep Field ACS HRC auto-parallel data were reduced by a dedicated team from the ST-ECF composed of:
|with extra help from:|