1. Home
  2. Forums
  3. Variable Star Observing
  4. Photometry

Ic and Rc standard magnitudes from APASS

spp
Affiliation
American Association of Variable Star Observers (AAVSO)
Sat, 06/27/2015 - 00:22

I see that some AAVSO comp star sequences contain standard magnitudes for Rc and Ic filters which are reported to come from APASS (29 in the footnote).  As far as I'm aware,  APASS observations don't use these filters.  How are these magnitudes determined? 

Phil

HQA
Affiliation
American Association of Variable Star Observers (AAVSO)
Sat, 06/27/2015 - 00:39
APASS Rc/Ic

Hi Phil,

If you compare SDSS r' and i' with Cousins Rc and Ic, you will see that the bandpasses are pretty similar.  Several authors have produced transformations from SDSS r'i' to Cousins RcIc.  The transformation we use comes from Jester et al. 2005.  So you are correct that the native filters for APASS do not include the Cousins filters, but what we provide for comparison stars is pretty close to the usual Standard.

Arne

cmorsoc
Affiliation
American Association of Variable Star Observers (AAVSO)
Wed, 08/23/2017 - 08:13
APASS Rc/Ic

Hi, so... Does this mean that the R magnitudes available at seqplot->APASS are Rc?

Thanks

Carlos

HQA
Affiliation
American Association of Variable Star Observers (AAVSO)
Wed, 08/23/2017 - 11:44
Rc magnitudes

HI Carlos,

Yes, the seqplot magnitudes (derived from the APASS native r'/i') are Rc and Ic.

Arne