From: Peregrine McGehee To: Stupendous Man Cc: , , , , , , Subject: February 2002 look at nebula 1. Dear all, >From SDSS run 2968 it appears that the knot just to the NW i, like HH22 knot A to the NE, is bright in the r band. It is also clearly detached from the emission surrounding the protostar. Details on the attached figures: o The flux at each point was computed as nanoMaggies/arcsec^2 by using 0.8 arcsec radius circular apertures spaced on 0.4 arcsec [the SDSS imager pixel size] grid. The background, which was defined as the minimum flux in the field, was subtracted off. The pseudo-color table is mapped onto a log flux scale ranging from 0.1 (red) to 10.0 (blue) nanoMaggies/arcsec^2. o The lower row shows "hardness ratios" = (a-b)/(a+b) on a linear scale between -1.0 (red) and 1.0 (blue) for r-i, i-z, and r-z. No attempt was made to correct for low SNR regions. o The very bright point in the z band image coincident with the HH22 A knot is, alas, a cosmic ray hit. o The astrometry as derived from the WCS GSS header is somewhat off, especially in RA - I'll ask Doug Finkbeiner tomorrow at the collaboration meeting. - Peregrine -- Peregrine M. McGehee Department of Astronomy New Mexico State University, Las Cruces, New Mexico 2.