NASA InfraRed Telescope Facility(IRTF), Institute for Astronomy, University of Hawaii

Zero Point Monitoring

We record and plot measurements of the Opihi telescope's zero point over time across different filters. This interactive figure above tracks the zero point measurements taken within the last 48 hours of the most recent Opihi photometric observation.

There are the following filters in Opihi's filter wheel. (For more information, see the Opihi documentation.) The expected detector zero point magnitudes $Z_p$ provided are for photometric nights. Lower magnitude measurements signify a worsening atmospheric sky quality. These values have also been added to the plot for refrence.

Filter Name Photometric Zero Point Notes
c $Z_p(c) \sim 22.5$ This is not actually a true photometric filter so a true zero point value cannot be determined.
g' $Z_p(g) = 21.6$
r' $Z_p(r) = 21.2$
i' $Z_p(i) = 21.1$
z' $Z_p(z) = 20.5$
1 $Z_p(1) = ?$ A placeholder for a possible new filter.
2 $Z_p(2) = ?$ A placeholder for a possible new filter.
b $Z_p(2) = \infty$ This "filter" is a block/blank, a solid opaque filter for the purposes of taking darks. The photometric zero point cannot be determined.

Contact Mike Connelley for further information and assistance.