J and H Band Comparison Stars for Alf Ori
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.