Messed with parameters of celldetect and dmextract, region shapes, single and multiple chip exposure maps, to see if I could get closer results for the two threads; still pretty big discrepancies between the two.

Made table to see the general difference between results from celldetect and dmextract, as compared to each sources distance off the pointing axis of the observation. Values in table were position, counts (in the .5-8KeV range), error in counts, exposure time, flux (counts/exposure time- approximation), Del_counts (dmextract-celldetect results), Del_Pointing i.e.{[(RA1-RA2)*3600*cos(DEC1)]^2+[(DEC1-DEC2)*3600]^2}^(1/2)

Though the sample set too small to see if there is a direct correlation, it looked as though generally counts were more alike closer to pointing axis.

Compared these fluxes (which as expected differ somewhat depending on the extraction method) to Webpimms estimates based on ROSAT count rates.

Pimms estimates were as follows (temperature range between .06-.1KeV, as calculated in "The Coolest X-Ray Emitting White Dwarfs"):

0931: n_H=1.42e20, .017 cps ROSAT, temp=.1keV:
ACIS I= 2.175e-2 cps
ACIS S= 1.06e-1 cps
0.06KeV:
ACIS I=3.978e-3 cps
ACIS S=6.946e-2 cps

1532: n_H=1.7e20, .012 cps ROSAT, temp=.1keV:
ACIS I= 1.636e-2 cps
ACISS= 7.707e-2 cps
0.06KeV:
ACIS I=3.139e-3 cps
ACIS S=5.068e-2 cps

For 0931 (located at 142.8454132 36.3692741), the closest match to this estimated flux was at 143.03993 36.500260. This source is on the ACIS I array and has a flux of approximately 2.8e-2 cps (cdetect) or 4.04e-2 cps (dmextract). The closest source to the expected position of the WD was at 142.80575 36.378942; this is on the ACIS S array and it's flux (approx 5.1e-3 or 5.8e-3) is an order of magnitude lower than the estimated chandra flux, so it seems more probable to me that the former is the more probable source (not sure if that is an ok assumption- is the astrometry good enough that proximity is more indicative of possible matching.....?)

For 1532 (located at 233.1062 47.45025) both sources detected were found on the ACIS S array; the closest both in flux and position to estimates was one at 233.18429 47.401489 with a flux of approx. 9.396e-3 (cd) or 1.167e-2 (dme) cps, so if in fact one of these is a match, it seems like the most probable of the two.

These estimates were based on my assumption that the ROSAT data was taken with the HRI. Were it with the PSPC, with the same other parameters, the estimates would be:

0931: ACIS I- 5.108E-03 cps
ACIS S- 2.489E-02 cps

1532: ACIS I- 3.998E-03 cps
ACIS S- 1.883E-02 cps

I'm in the process of comparing these sources with SDSS using image list and cross ID, to see if there are matches.

Also retrieved and played around a bit in ds9 with G16.7. Next steps are to get counts, try by hand and with celldetect or wavedetect (extended source), make exposure map, play with gator and other matching catalog exercises...