[vsnet-chat 2437] (fwd) V1494 Aql prediscovery negative data (Pereira)

[Taichi Kato <tkato>]

(fwd) V1494 Aql prediscovery negative data (Pereira)

Date: Thu, 09 Dec 1999 18:01:15 +0000
From: Alfredo Pereira <apereira@fc.ul.pt>
Subject: Last negative searches in Aql before discovery

Nov 25, 1855-1916 UT, 14x100B, possibly <8.5:, quite surely <7.5:
Nov 25, 1956-2008 UT, 14x100B & 9x34B, quite surely <7.5:

Nov 26, 1853-1901 UT, 14x100B, quite surely <7.5: (through cirrus)
Nov 26, 1956-2041 UT, 14x100B & 9x34B, possibly <8.5:, quite surely <7.5:
(good transparency with scattered Altocumulus lenticularis)

Nov 27, 1948-2006 UT, 14x100B, possibly <8.5:, quite surely <7.5:
(very good transparency)

It is difficult to say what the probability of detection versus 
limiting magnitude is.  Anything brighter than about 6.7-7.0 
should be easily picked up, _if_ I do not scan around it and miss 
it.  I know from experience that it is easy to think one has gone 
to all parts of one's area, but in fact one may have missed small 
portions.  Peter Collins swept right around 5th mag N Her 91 found 
by George Alcock!  This is always a great concern for me, and I 
make every effort to scan completely.  I try to cover with the 
9x34's the areas already covered with the 14x100's if I have time.

If I am not doing it hastily because of threatening clouds, or 
something like that, I think that the probability of detection 
is still close to one down to mag 7.5.  The range of mag 7.5-8.5 
is a grey area, with the probability dropping to close to zero 
at fainter mag 8.5. 

The following stars are the faintest memorized near the nova, but 
I only go to that limit in searches with the 14x100's: GSC 4733097 
(V=8.98; B-V=+0.37 Tycho), and GSC 473774 (V=8.90; B-V=+0.51 Tycho).
However, this one is also near the nova, but is not memorized: 
GSC 4735917 (V=8.66; B-V=+0.88 Tycho).

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