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[vsnet-alert 2724] U Sco sequence (Sumner and Henden)
- Date: Sun, 28 Feb 1999 17:44:50 +0900 (JST)
- To: vsnet-alert
- From: Taichi Kato <tkato>
- Subject: [vsnet-alert 2724] U Sco sequence (Sumner and Henden)
- Sender: owner-vsnet-alert@kusastro.kyoto-u.ac.jp
From owner-vsnet-chat@kusastro.kyoto-u.ac.jp Sun Feb 28 15:04 JST 1999
From: "Bruce Sumner" <bas@bom.gov.au>
To: aavso-discussion@physics.mcmaster.ac, vsnet-chat@kusastro.kyoto-u.ac.jp
Date: Sun, 28 Feb 1999 17:01:24 +1100
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Subject: [vsnet-chat 1667] U Sco sequence
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Subject: Sequence for U Scorpii
The forthcoming rapid fading of U Sco would be made easier for observers
to follow if there was a standard comparison star sequence. I have prepared
such a sequence, for use once the variable falls below Hipparcos/Tyccho
limits. This sequence is primarily derived from Arne's recently available
CCD photometry. I have added some additional photoelectric photometry values
obtained in 1970 by Barry Menzies to fill in the bright end of the sequence.
These bright values have no colours and are probably accurate to about 0.05.
However they are satisfactory for visual estimates, as indeed they form
part of the sequence used by the Variable Star Section of the Royal
Astronomical Society of New Zealand (VSS RASNZ).
I propose that this sequence be called the 'RASNZ' sequence in anticipation
of its adoption by the VSS RASNZ as its official sequence for this variable.
This would distinguish it from other sequences that may be used during the
fading of this very interesting event.
Kato's VSNET chart and sequence for U Scorpii, dated 7 April 1995, is
about 0.10V too bright across its entire sequence. The following accurate
sequence should be used in preference to Kato's magnitudes. In particular
the adopted v values in the last column should be used by all visual
observers to ensure consistency of estimates.
___________________________________________________________________________
112 U SCORPII (NR) Range: 8.0-18.5V
16 22 30.779 -17 52 42.94
Magnitude in .dat file: V=18.510 B-V=0.459
ID RA (2000) DEC X Y N V ERR B-V ERR Adopted
v
1 16 23 16.1 -17 50 15 648 150 10.61 10.6
2 16 22 25.8 -18 02 59 -72 -616 10.94 10.9
3 16 22 54.0 -17 45 08 332 454 11.53 11.5
4 16 22 09.4 -17 53 15 -306 -32 3 12.565 0.015 0.906 0.010 12.6
5 16 22 45.8 -17 51 52 214 51 3 12.588 0.005 1.238 0.003 12.6
6 16 22 08.1 -17 52 57 -325 -14 3 12.730 0.006 0.927 0.006 12.7
7 16 22 27.7 -17 48 57 -45 226 3 12.764 0.005 1.511 0.007 12.8
8 16 22 46.5 -17 57 01 224 -258 3 12.783 0.000 0.795 0.007 12.8
9 16 22 44.4 -17 47 32 194 311 3 13.167 0.005 0.641 0.008 13.2
10 16 22 31.7 -17 01 13 14 -510 13.74 13.7
11 16 22 11.9 -17 57 33 -270 -290 3 14.286 0.009 0.870 0.014 14.3
12 16 22 22.3 -17 54 10 -121 -87 3 14.489 0.006 1.174 0.003 14.5
13 16 22 29.2 -17 54 50 -23 -127 3 14.628 0.005 1.168 0.002 14.6
14 16 22 38.9 -17 56 51 115 -248 3 14.751 0.005 0.967 0.009 14.8
15 16 22 36.8 -17 51 55 86 48 3 15.098 0.006 0.837 0.006 15.1
16 16 22 27.5 -17 54 15 -47 -92 3 15.494 0.016 0.818 0.015 15.5
17 16 22 24.5 -17 54 22 -90 -98 3 15.649 0.024 0.870 0.014 15.6
18 16 22 25.6 -17 51 34 -75 69 3 15.863 0.006 1.120 0.015 15.9
19 16 22 12.8 -17 49 31 -257 192 3 16.016 0.017 1.129 0.019 16.0
20 16 22 42.0 -17 52 42 160 1 3 16.247 0.014 0.872 0.012 16.2
21 16 22 36.2 -17 51 22 77 81 3 16.383 0.016 0.863 0.020 16.4
22 16 22 29.2 -17 52 19 -22 24 3 16.697 0.019 0.856 0.038 16.7
23 16 22 27.9 -17 51 32 -41 71 3 16.918 0.009 0.791 0.009 16.9
24 16 22 30.3 -17 53 19 -7 -36 3 17.354 0.338 1.282 0.329 17.4
___________________________________________________________________________
Note that positive X and positive Y offsets are north & east respectively.
The four magnitudes without B-V values and errors are from B. Menzies,
Circ. 171, VSS RASNZ, 1971. All other magnitudes are derived from CCD
photometry obtained by Arne Henden (see vsnet-chat 1664).
Menzies measured three other stars in V that were also measured by Henden.
The letters are from RASNZ chart 100 (and Circ. 171).
Menzies Henden
k 12.63 12.588
l 12.65 12.565
m 12.84 12.764
Star 24, just south of U Scorpii, has large errors and should not be used
as a comparison star. I will replace the faint end of the sequence with
additional stars in a few days time.
There is a large gap in the sequence between 11.5 and 12.6. If anybody
knows of some V values in this range I would appreciate advice so that
I can add them to this sequence.
Bruce Sumner
28 February 1999
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