Carina IRSF/SIRIUS Data 2003/04 by WP Chen 2004/4/13

Kaushar sent me a file j7j8both.txt which contains the positional and photometric data of stars in the overlapping region of the J-band images between pointing #7 and #8. It contains 74 stars. I wrote a small idl procedure j7j8both.pro to read in the data, and plot the histogram of (j7-j8) [mag] as shown below. It is plotted with the U Tubingen routine

i> plothist, mj1-mj2, bin=0.05

The single outlier to the left, J1-J2 = -0.769 belongs to the last data entry, #74 (#73 in IDL!).

Kaushar sent me (April 13, 2004) a revised file, j7j8new.txt, now with 73 stars, which corrects the error in negative declination values and contains double-precision ra and dec in degrees. I also modified my program, now called compboth.pro to take care of some double-precision variables. The original second entry in j7j8both.txt has been left out from the revision j7j8new.txt,

10 45 26.170 -59 50 4.430 161.35904 -58.16544 16.913 0.013

10 45 23.493 -59 50 2.240 161.34789 -58.16604 17.592 0.032

The last entry is still the strangest of all. The RA difference (RAS1-RAS2) is all positive and averages to ~+0.02”, but entry #73 has -0.02. The DEC difference is of the same order, with a naveraged offset of -0.02”. The J-magnitude difference averages to -0.04 mag, except the last entry (#73) which has J1-J2 = -0.769. #73 reads below. It could be a mismatch.

10 45 23.990 -59 43 44.150 161.3499583 -59.7289306 14.768 0.243

10 45 24.012 -59 43 44.080 161.3500500 -59.7289111 15.537 0.009

For j7j8 data: the J-mag, RA and DEC differences

1004.06.14

Final Scaling Kaushar worked out the proper scaling for each pointing, for each filter, shown below.

J band

H band

K band

2MASS data

I used the (new) RADAR interface at IRSA http://irsa.ipac.caltech.edu/ to get the 2MASS point sources. Within a radius of 15’ centered around Eta Carina, there are 14,356 entries. I selected only those with S/N > 10 in all J, H, and Ks bands, ending up with 6727 entries, and saved as the file 2mass20040415.txt.

The format of the file for the first columns is

ra dec J sig1_sig2 S/N H sig1 sig2 S/N K sig1 sig2 S/N

161.714680 -59.709854 14.696 0.051 0.053 37.5 14.121 0.063 0.064 33.5 13.937 0.076 0.076 19.6

The spatial distribution is as follows,

The J mag sensitivity follows,

The (J-H) versus (H-K) diagram follows,