In the VSX Magnitude column, the entries sometimes have a range of magnitudes, like 12.54 to 13.14, which I understand. However some of the entries are, for example, 8.120(00.066). How is this interpreted? Is this a +/- range?
Also, what is the meaning of the, for example, ‘Ic’ suffixes, and ‘V’, ‘G’, ‘g’?
I would appreciate any help with this. I am just getting started using the DB as part of a class.
Hi,
I do not think the 8.120 (0.066) is a +/- range but just a range starting from 8.120.
The other suffixes are filter namings, IC and V being photometric filters, g is part of the Sloan filter set (griz) and G is for Gaia filters.
I hope this helps.
Josch
Hi Timothy,
The values given in brackets are amplitudes. The recorded difference between maximum and minimum. Two main reasons to show this instead of a range:
- The source catalog / discovery paper published it like that.
- The recorded variations were made a non-standard passband (e.g. TESS), so a mean standard magnitude is given and then the amplitude as seen in that non-standard passband.
When an amplitude is given, the maximum magnitude becomes a mean magnitude. This means that you can’t add or subtract the amplitude to that magnitude to obtain a range, because the mean magnitude will vary depending on several factors, like the number of observations (if you have just a few observations, they may have been all randomly taken at maximum or minimum), the variability type (the mean magnitude of a detached eclipsing binary will be pretty close to the maximum value, while the mean magnitude of a flare star will be almost the same as the minimum magnitude), etc.
Cheers,
Sebastian
2 Likes
Thank you guys, that helps a lot. Myself and another student are downloading a lot of star data and now I understand what I can filter and what I don’t need to.
Tim