[Last Change: 01 Mar 2011 (rev 2)]

UV and IR PSF

The Chandra Optics were not calibrated in the IR or UV, but certainly do reflect and focus images from IR and UV sources. The detector assemblies include filters designed to reduce or eliminate the possibility of such photons' accumulation by the detector. Several observations on both ACIS-I and ACIS-S were made to quantify any IR and UV light leakage, with Betlegeuse observed for the former and Vega for the latter.

Observations

The complete (as of 2008 May) list of ACIS RAW mode data is:

OBSID Target CCD Dither Yoff Xoff 2593 Betelgeuse I0 Nominal 4.70 -5.68 3366 Betelgeuse I1 Nominal -4.00 -3.68 3367 Betelgeuse I2 Nominal 4.70 2.50 1856 Betelgeuse I3 Off 0.00 0.00 3678 Betelgeuse I3 Nominal 0.00 0.00 5048 Betelgeuse I3 Nominal 0.00 0.00 5963 Betelgeuse I3 Off -0.33 0.00 6447 Betelgeuse I3 Nominal -0.33 0.00 1855 Betelgeuse S3 Off 0.00 0.00 3679 Betelgeuse S3 Nominal 0.00 0.00 5049 Betelgeuse S3 Nominal -0.33 0.00 5964 Betelgeuse S3 Off -0.33 0.00 6448 Betelgeuse S3 Nominal 0.17 0.00

OBSID Target CCD Dither Yoff Xoff 2586 Vega I3 Nominal 0.00 0.00 36 Vega I3 Off 0.00 0.00 3685 Vega I3 Nominal 0.00 0.00 5046 Vega I3 Nominal 0.00 0.00 5961 Vega I3 Off -0.33 0.00 6445 Vega I3 Off -0.33 0.00 2587 Vega S3 Nominal 0.00 0.00 3686 Vega S3 Nominal 0.00 0.00 37 Vega S3 Off 0.00 0.00 5047 Vega S3 Nominal -0.33 0.00 5962 Vega S3 Off -0.33 0.00 6446 Vega S3 Off 0.17 0.00

This list includes data where the dither was not turned off. It may be possible for some adventurous soul to correct the dithered data.

Observations without dither

This is a list of those data taken with dither turned off. Click on the image to get a FITS file. See below for how the images were created.

ACIS I3	ACIS S3
OBSID Target Yoff Xoff nmed Image 36 Vega 0.00 0.00 11 1856 Betelgeuse 0.00 0.00 9 5961 Vega -0.33 0.00 11 5963 Betelgeuse -0.33 0.00 11 6445 Vega -0.33 0.00 13	OBSID Target Yoff Xoff nmed Image 37 Vega 0.00 0.00 5 1855 Betelgeuse 0.00 0.00 5 5962 Vega -0.33 0.00 5 5964 Betelgeuse -0.33 0.00 5 6446 Vega 0.17 0.00 5

Data Reduction

ACIS RAW images are images as read out from the detector (before event processing is performed) with additional bias columns added (eight per node).

Observations were processed with rawmedadd (available in our download area, here ), a Perl script using PDL which

1. bias subtracts each frame using the bias columns
2. groups the frames
3. generates a median image from each group
4. sums the median images.

The median process is used to help remove cosmic ray blooms. The number of frames in each group was adjusted by eye to remove the majority of cosmic ray blooms. There is significant residual (non-source related) structure in the resultant image.

The data were processed with the nmed parameter as specified in the above table.