I've uploaded to VSP the calibration from BSM_Berry for the 1.4x2.2 degree field centered on NGC 3532; approximate coordinate center 11:05:12 -58:44:01. This calibration goes from 7<V<11mag and includes BVRI. You can plot it using the center coordinates and selecting "Standard Field". This cluster is pretty nice, not too dense and having a color range from about 0<(B-V)<1.7. I think Matt did a good job in selecting it!
Some caveats... The Bright Star Monitors have coarse pixelization, and so blends in crowded fields are common. The aperture size is 30arcsec, so don't trust stars very close to the cluster center. I've removed by hand several known variables, but others may still exist in the data set. It would be good for someone to go through VSX and remove others, and for observers to try these stars for calculating their coefficients and finding what stars don't fit the trend line (typically blends) so that we can clean up this set. There are over 300 uploaded stars, so we can remove a few without impacting anything!
I have other data from other telescopes, including fainter observations using OC61. I'll merge those values into the current table in the future.
The BSM_Berry observations of NGC 1252, the remaining southern standard cluster, have too much scatter and so I haven't uploaded that dataset yet. I want to look at other photometry and see if I can find the reason for the scatter. Hopefully, I'll have time to do that in the near future.
Arne
Thanks Arne,
These standards will be very useful for those of us south of the equator. I'll make good use of them when NGC 3532 is convenient to observe. Looking forward to the NGC 1252 standards when they are available too. Cheers,
Mark
I'll get a TG update out in the next couple of weeks to support this field.
Gordon
Gordon,
I replied to you and Ken on another thread about checking NGC 3532 standards but cannot seem to find it! I'm fairly new to the forums and not yet worked out the 'schema'.
Tex