Report on a New 12.5" f/8 Hyperion Telescope

Dick Steinberg

4/29/10

The Hyperion is a telescope manufactured by Starizona based on a variant of the Cassegrain design due to Harmer and Wynne.  The paraboloidal primary and spherical secondary mirrors are followed by an afocal corrector to yield an astrographic-quality 70-mm diameter diffraction-limited image circle.

Here is a view of the new Hyperion which Don d'Egidio and I picked up at NEAF and then placed on my backyard AP1200.

So far, with limited clear skies and the usual suburban light pollution, I have managed only a few trial images with the new scope using the Apogee U16M large-chip ccd camera. Note that the persistent dust donuts visible in most of these images are currently under investigation and are thought to be caused, at least in part, by the local high-pollen season and not by any particular defect in the camera/telescope system.

Here are a few of the first images, taken during a period of near full moon:

M51 in CVn (30 minutes);

M97 in UMa (30 minutes);

M101 in CVn (60 minutes);

NGC2903 in Leo (15 minutes);

NGC3718 in UMa (28 minutes).
 

Concerning the dust-donut problem, in an animated sequence of flat-field images, the arrival of a few of the dust particles is clearly seen. Short of using Photoshop, there is no easy way to remove artifacts from the finished images caused by such time-dependent events.  However, we have made some progress in eliminating the dust donuts, as shown by recalibration of the above image of M101 with a subset of the original 24 flats. Some sort of dust prevention scheme is called for. 

One of the master flats, shown here, indicates that the corner-to-corner field illumination is uniform at the level of about 2%, a very satisfactory result.

The general conclusion is that the Hyperion is working as designed, with a very wide, flat, evenly-illuminated 50 arcmin x 50 arcmin FOV which nicely covers the very large KAF16803 chip (37mm by 37mm). The problems seen so far, dust donuts near the chip and some sort of internal reflection, look like they can be fixed.

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current setup:

Telescope: 0.32m f/8 Hyperion Harmer-Wynne flat-field design -- FL 2540mm

Mount: AP1200

Camera: Apogee U16M - 4096x4096  nine micron square pixels (unbinned)

motorized 3.5" Feather Touch focuser controlled by FocusMax

image acquisition and processing with MaxIm DL v5.07  - calibration and screen stretch only - no PhotoShop

automated control with CCD Commander v1.6

1 min subs unguided - 1.46 arcsec/pixel  - binning 2x2 - chip temperature -15C