Analysis of consistently deblended calibration standards using the OPS test nights run in early July, 2001. All standards having either deblend percentages >=10% or deblends consistently found in all three bands are noted below. Note that the statistics do NOT include any data from the problematic northern data in June and July 1997.
90004, 24 stds, 95 apparitions
------------------------------
All ok.
90009, 22 stds, 96 apparitions
------------------------------
All ok.
90013, 40 stds, 138 apparitions
-------------------------------
All ok.
90021, 26 stds, 138 apparitions
-------------------------------
s90021_24 Deblended 9% of the time. As with the source below, all the
deblending is restricted to two dates, 971017n (scans 16-20 and
44-49) and 990923s (scans 66, 115, 118). In all these cases the
seeing shapes are poor (Jsh between 1.10 and 1.40) although for
the later date the aspect ratios are excellent. We believe this is
more a problem with deblending than with this std. KEEP.
[I started looking at this field before all the analysis was run,
and based on a limited data set it appeared to be deblended more
than 10% of the time. This std fell below this threshold in the
final analysis, but I leave these comments here anyway.]
s90021_45 Deblended 11% of the time. All of this deblending occurred on
971017n (scans 17-18, 20-21, 44-49) and 990923s (scans 115-117),
with none of it occurring on 981028n, 000902s, 001126n, 981104n,
or 991020s. As with the standard listed above, we think this is
not a problem with this source. KEEP.
90067, 34 stds, 156 apparitions
-------------------------------
s90067_39 Deblended 20% of the time. It appears that there may be a faint
companion to the NW. REMOVE.
s90067_52 Deblended 10% of the time. It's not obviously double, though there
might be a slight hint of elongation at Ks. REMOVE.
90091, 24 stds, 48 apparitions
------------------------------
s90091_38 Deblended 18% of the time. Most of the deblending occurs on 990523n
(6 of 9). This source looks clean on the images, and the offending
scans from 990523n were the first taken that night and have bad
I2min/I2maj ratios at Ks. As the duplicity is inherent to the data
and not the star, this std should not be removed. KEEP.
90121, 35 stds, only 5 apparitions
----------------------------------
All ok, though there are very few observations of this field in the OPS test
database.
90161, 44 stds, 138 apparitions
-------------------------------
s90161_2 Deblended 16% of the time. All instances of deblending are confined
to two dates, 971017n and 971116n. In some of these scans the
I2min/I2maj ratios are not great (but in some they look just fine!)
Again, this problem seems to be due to the quality of the data and
is not a problem inherent to the source. KEEP.
s90161_43 Deblended 12% of the time. The same note as above applies. KEEP.
s90161_51 Deblended 14% of the time. Ditto. KEEP.
90182, 35 stds, 49 apparitions
------------------------------
s90182_5 Deblended 25% of the time. All but one instance of deblending occurs
on 971017n. KEEP.
s90182_25 Deblended 31% of the time. This one is deblended on many different
dates. Images show that it has a faint close companion due north.
REMOVE.
s90182_32 Deblended 26% of the time. All but one instance of deblending occurs
on 971017n. KEEP.
s90182_33 Deblended 67% of the time. Deblended on many different dates. Images
show that there is a faint component to the west. REMOVE.
s90182_45 Deblended 10% of the time. All instances of deblending are from the
night of 971017n. KEEP.
s90182_51 Deblended 29% of the time. Most of the deblending comes from 971017n
but there are also occurrences on 980927n and 980613n. Images show
this source to be free of any obvious confusion. KEEP.
s90182_53 Deblended 27% of the time. All instances of deblending are from two
nights, 971017n and 980613n. Images show that source is free of
confusion. KEEP.
s90182_56 Deblended 23% of the time. All instances of deblending are from
971017n (except for one on 980613n). KEEP.
s90182_64 Deblended 10% of the time. All instances of deblending are from
971017n. KEEP.
s90182_65 Deblended 12% of the time. Again, all instances of deblending are
from a single night, 971017n. KEEP.
s90182_66 Deblended 25% of the time. Instances of deblending are scattered
over several nights, but the big culprits are again 971017n and
980613n. Images show the source to be free of obvious confusion.
KEEP.
s90182_71 Deblended 10% of the time. All instances of deblending are confined
to 971017n. KEEP.
s90182_73 Deblended 24% of the time. All instances are again confined to
971017n. KEEP.
90191, 35 stds, only 18 apparitions
-----------------------------------
All ok.
90217, 27 stds, 96 apparitions
------------------------------
s90217_5 Deblended 21% of the time. Deblended on many scattered nights.
Images show a faint star to the nortwest that is probably confusing
the fitted photometry. REMOVE.
90234, 27 stds, 48 apparitions
------------------------------
All ok.
90247, 37 stds, 97 apparitions
------------------------------
s90247_1 Deblended 19% of the time. Deblended on scattered nights. Images
show that it's unconfused with maybe just hint of a faint companion
to the east. KEEP.
s90247_7 Deblended 11% of the time. Deblended on scattered nights. Images
show no problems. KEEP.
s90247_13 Deblended 12% of the time. Deblended on just three nights, and
images show it's clean. KEEP.
s90247_15 Deblended 10% of the time. Deblended on just three nights, and
images show it's clean, too. KEEP.
s90247_18 Deblended 64% of the time. Obviously this one's different from the
others based on its high percentage of deblending. Image show that
this source is elongated SE-NW. REMOVE.
s90247_42 Deblended 12% of the time. Images show it's ok. KEEP.
s90247_44 Deblended 10% of the time. Images show it's ok. KEEP.
s90247_57 Deblended 12% of the time. Images show it's ok. KEEP.
s90247_59 Deblended 13% of the time. Images show it's ok. KEEP.
s90247_61 Deblended 10% of the time. Images show it's ok. KEEP.
s90247_64 Deblended 10% of the time. Images show it's ok. KEEP.
s90247_67 Deblended 10% of the time. Images show it's ok. KEEP.
s90247_72 Deblended 16% of the time. Images show it's ok. KEEP.
s90247_73 Deblended 14% of the time. Images show it's ok. KEEP.
s90247_75 Deblended 13% of the time. Images show it's ok. KEEP.
90266, 23 stds, 130 apparitions
-------------------------------
All ok.
90272, 22 stds, 48 apparitions
------------------------------
All ok.
90273, 21 stds, 54 apparitions
------------------------------
s90273_18 Deblended 17% of the time. Deblended across a range of dates. Images
show that this source is slightly elongated to the SW. REMOVE.
90279, 27 stds, 54 apparitions
------------------------------
s90279_4 Deblended 17% of the time. Deblended on three different nights.
Images show that there is a faint companion a few pixels away to
the SW that may cause confusion problems during poorer seeing.
REMOVE.
90290, 21 stds, 68 apparitions
------------------------------
s90290_43 Deblended 11% of the time. Deblends occur on scattered dates. There
is a much fainter source to the SW that could potentially cause
problems. To be on the safe side, this std should probably be axed.
REMOVE.
90294, 12 stds, 126 apparitions
-------------------------------
All ok.
90301, 31 stds, 90 apparitions
------------------------------
All ok.
90312, 26 stds, 258 apparitions
-------------------------------
All ok.
90330, 43 stds, 18 apparitions
------------------------------
s90330_28 Deblended 11% of the time. Source appears fine on images. KEEP.
s90330_29 Deblended 28% of the time. Images show a faint object to the SW
that will confuse photometry. REMOVE.
s90330_47 Deblended 11% of the time. Source appears fine on images. KEEP.
90533, 36 stds, 154 apparitions
-------------------------------
All ok.
90547, 25 stds, 66 apparitions (a very crowded cal field)
------------------------------
s547_15 Deblended 14% of the time. There is a faint source to the east that
can confuse photometry. REMOVE.
s547_1 Deblended 40% of the time. Images show a star to the NW that can
confuse photometry. REMOVE.
r547_1 Deblended 38% of the time. There is a faint source to the NNW that
will confuse photometry. REMOVE.
r547_26 Deblended 16% of the time but is routinely deblended in all three
bands. There is a source almost due south that will confuse the
photometry. REMOVE.
r547_16 Deblended 22% of the time. There is a close source to the NW and
another to the NW of it that make for confused photometry. REMOVE.
r547_7 Deblended 52% of the time and is routinely deblended in all three
bands. There is a source to the SW that will cause confusion with
this std. REMOVE.
90565, 35 stds, 245 apparitions
-------------------------------
s90565_15 Deblended 19% of the time, almost always at J band. Image shows
very close, faint bkg source due west of std. REMOVE.
s90565_40 Deblended 42% of the time. Images show that source is definitely
double, a fainter source lying due east of std. REMOVE.
s90565_42 Deblended only 9% of the time but deblended consistently in all
three bands. Images do not show obvious duplicity, though
the source may be slightly elongated at Ks. REMOVE.
90808, 12 stds, 117 apparitions (a very crowded cal field)
-------------------------------
s90808_11 Deblended 13% of the time. Deblended on many nights. Images show
that it may be slight elongated NW-SE. REMOVE.
s90808_16 Deblended 48% of the time. Deblended on many nights. This source is
confused on both the NW and SE sides by very close companions.
REMOVE.
s90808_19 Deblended 32% of the time. Deblended on many nights. This std has a
very close neighbor due south. REMOVE.
s90808_21 Deblended 21% of the time. Deblended on many nights. There is a very
close source to the NW. REMOVE.
90813, 32 stds, 240 apparitions
-------------------------------
All ok.
90860, 20 stds, 192 apparitions
-------------------------------
All ok.
90867, 22 stds, 54 apparitions
------------------------------
s90867_15 Deblended 15% of the time. Deblended on many nights. The image looks
ok however, but to be safe (and since there are plenty of stds in
this field already) it should probably be dropped. REMOVE.
90868, 17 stds, 147 apparitions
-------------------------------
s90868_15 Deblended 28% of the time. Deblended on many different nights. The
images shows that it's possibly elongated east-west, but is in an
uncrowded field otherwise. It's best to leave this one out of the
stds list, I think. REMOVE.
90893, 25 stds, 102 apparitions
-------------------------------
s90893_41 Deblended (with "upl" flags) only 1% of the time but often deblended
in multiple bands simultaneously. Images don't indicate that it's
a problem with confusion, but it should probably be removed from
the list anyway. REMOVE.
92026, 39 stds, 18 apparitions
------------------------------
All ok.
92202, 16 stds, 30 apparitions
------------------------------
s92202_16 Deblended 10% of the time. Source looks clean, and since the number
of apparitions is small anyway, I think we should keep this one.
KEEP.
92397, 36 stds, 72 apparitions
------------------------------
All ok.
92409, 34 stds, 94 apparitions
------------------------------
All ok.