Mark IV at Flagstaff, Arizona

The very first Mark IV to be installed away from Tom's base in Batavia was given to Arne Henden, an astronomer at the US Naval Observatory. Tom drove it down to Arizona and handed it over on Aug 28, 2000. Read his account of the trip. Here are Tom and Arne in front of the telescope:

Arne has set it up on the "Polaris Pier" of the Flagstaff station (click on the image below for a larger version):

One of the first test images taken with the camera is shown below. This 60-second V-band exposure shows M11 and part of the Milky Way (it has been rotated so that North is up and East to the left). Click on the image for a larger version.


Arne Henden writes on 9/11/2000:

[The figure below] is the difference between instrumental measures and true V measures for the Landolt standard region SA92, taken around moonset on 000910 with a 152 second exposure. The mean value of the difference (~2.5mags or so) is irrelevant; it is the scatter that is important. Note that to about V=13 the points scatter around a pretty constant value, with some of the scatter due to Poisson noise and some due to the slight offset of the TASS V filter from the standard filter bandpass (the stars range 0.422 < (V-I) < 1.836, and I haven't done any transformation yet). Still, the RMS error is just a couple of percent. However, after V=13 you see a definite systematic error that looks like a magnitude effect. I'll have to look at that in more detail.

Here are subsections of the pictures of SA92 upon which the graph is based. The subsection is roughly one-quarter of the entire image -- I [the editor] have cut it down for ease of viewing. You can click on the images to see larger versions. The center of the camera's field of view is at the upper-left corner of these subsections, and the outer corner of the camera's field of view is at the lower-right corner of these subsections. You can see the image distortion at the corner, especially in the V-band picture.

All pictures have been rotated 90 degrees counterclockwise so that North is up and East to the left.

First, a chart of the area, with and without star IDs:

Now, the V-band picture. The bright star at lower left is 20 Ceti, a red giant.

Finally, the I-band picture.


Arne has started some tests of the Mark IV system. Here are some of the results -- the descriptions are from Arne's E-mail to the TASS mailing lists, and all graphs are Arne's as well.