I will shortly (hopefully) be announcing the observational campaign on the nearby YSO TV Crateris. This is a double-double system with an extremely complicated environment, actually too interesting to be outlined here! See the excellent article in MNRAS for a full outline of the physical parameters. Periastron of each pair is due to occur this Summer so it would be great of we could have observations made now. Matthew Kenworthy who has done great work on deconstructing the system of V1400 Cen from its chaotic light changes suggests 2 - 3 points per night. Ideally we would already have some obs in the can, and monitoring should be for at least the next few months as well.
I have produced a sequence which includes Sloan filter values in g / r / i which is what Matthew used on the V1400 Cen project.
HI,
I am following this target already for more than 150 nights in BVI filters. Data are with the AAVSO database and here is a screen shot of them:
I am so far the only observer.
Josch Hambsch (HMB)
Hi Josch,
What are you using for Comp and Check stars? I only see one star at mag 9.3 shown on the AAVSO Chart. Perhaps the campaign organizer needs to contact Sebastian Otero to get a full Sequence set up…
Gary
ps: Target is way too low for my scope’s location at 37N
Hi Gary,
Campaign organiser (and sequence creator) here!
Unfortunately we can’t magic comp stars into existence where there are none, and this is not a particularly star-rich part of the sky - so when stuff like this happens we need to get a bit creative. VSP plots the variable at the FOV centre but you can also (as I’m sure you know) centre the FOV on a position. You are not the only one who has experienced ‘compstar dearth’ in this field, and I suggested to another observer that he pick another star to centre on:
Tyc 6654-457-1 whose position is:
11 21 50.70 / -24 59 41.9
so try plotting in VSP with that position, you may get more comps depending on the FOV size. Obviously a small FOV like ‘e’ scale will not include many bright stars.
Good luck!
Michael Poxon, Norwich, UK
YSO section leader / sequence team
What is the problem with adopting the two G-dwarf stars west (HD 98739) and northwest ((HD 98790) as comps? They are almost certainly stable, and have likely reliable APASS DR9 data with confirming ASAS-3 V mags.
\Brian
Brian, one of those 10.3m star is in the sequence. As the mags of those two stars are very similar, I only used one, and picked the one nearest TV Crt.
Several people have pointed out the lack of comparison stars. This is always going to be a problem when:
-
The variable is bright, in an average-to-poor field
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Observers ask for a deep-scale chart. There simply aren’t enough 8 - 9m stars in 30 sq min of sky away from the galactic plane!
This object meets both of those criteria.
Mike Poxon, sequence team / TV Crt campaign researcher
Thanks for your note Mike and best of luck with the Campaign.
Hi Gary,
I choose 2 stars of 10.2 mag one being from the sequence of the AAVSO (000-BQB-065) and the other is an APASS DR10 star (ApassDR10-065-2573780).
Regards,
Josch