Interline background

Thirty 300s Fowler 16 exposures from 20080322 were combined to make a single median 300s "sky" exposure, fiveminmed.fits. The constituents of this frame can be found at the data archive for the March engineering run (sources SN2005ip SDSS1624 N4449 TM1507 AMHe MKN59).

The figure below shows a log stretch of the final image. Continuum above the dark level is evident in all orders.

The plots below show dark subtracted (from the adjacent frame area) count levels in 300 seconds for the H-band order - first covering the entire order then for a portion of the order.

Crudely, if we have 60 DN/s at APO for a 10th magnitude star, the 0.1 DN/s here would be equivalent to the DN/spectral element from a 17.0 magnitude star.