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J and H Band Comparison Stars for Alf Ori

JimK's picture
Joined: 2013-02-19

I am looking for suggestions on comparison and check stars for Alf Ori in the J and H bands.  I have loaded one observation using all sky photometry utilizing some of the standards listed in Henden's article 'JHK Standards for Small Telescopes', JAAVSO Volume 31, 2002.  Reviewing other observations I see that observer RTH uses Alf Tau and Gam Ori for Comp and Check stars respectively.  A recent forum thread indicated HPO is starting an Orion project.  It would be beneficial if there was an agreed Comp and Check stars for Alf Ori in this band to facilitate comparison of observations.  (In Vermont nights that have conditions constant enough for All Sky photometry are few).  I note in VSX that Alf Tau is variable in the V band by about 0.2 mag.  Does anyone know of variability of this star in the J and H bands?  

On a related note I may be having some issues with transformations in these band.  My all sky observations agreed well with the standards when corrected for extinction and zero points (Standard error of 0.03 in J and 0.04 in H), and did not show any linear correlation between the instrumental magnitude and the H-J color index. Any other SP4 users with similar experience?

Any help would be appreciated.

Jim Kay

Aldebaran variations
Sebastian Otero
Sebastian Otero's picture
Joined: 2010-09-19

Hi, Jim,

>>> I note in VSX that Alf Tau is variable in the V band by about 0.2 mag.  Does anyone know of variability of this star in the J and H bands?

Actually there is no proof that such variability range was real. Checking the literature on the star reveals that the variations are smaller or equal to 0.03 mag.
The VSX entry has been revised.
Best wishes,

Sebastian Otero
VSX Team
American Association of Variable Star Observers

BVRIJH Standard Values
HPO's picture
Joined: 2010-07-23


Hi Jim,

Thanks for your post. I should be announcing the Orion Project shortly. I am still fine tuning the web site. You make a good point on the comaparison star magnitude values. I have struggled to find goog values. What I have on the web site is not complete and may be subject to some question. Different places state different values so I pick the ones that I feel are most reliable. The JAAVSO artice does not cover any of the stars used in the Orion Project.

If anyone knows the BVRIJH values for 
I would be most interesting in hearing about them. I have some of hte values, but not all.


Jeff (HPO)
Hopkins Phoeinx Observatory

UBVJHK Values for Bellatrix (HD35468)
JimK's picture
Joined: 2013-02-19

I retrieved the following from SIMBAD at the link below.  Still searching the Bibliographies.  Realize I do not have values for R and I.

U 0.54  B 1.42  V 1.64  J 2.15  H 2.36  K 2.38

AAVSO 49 Bay State Rd. Cambridge, MA 02138 617-354-0484