ETX-90 Deep Sky
An SBIG ST-7E camera was connected to a Meade ETX-90 via a Scopetronix adapter. This combination was mounted on a Vixen GP mount. The DC motor drives were modified to accept autoguider inputs from the camera. A series of 30 second exposures were used to verify the operation of the circuitry. Image data and autoguider control were carried out by use of CCDOps software from SBIG. No filters were used.
100 dark frames and 100 bias frames were collected during poor weather a week earlier. A “bad-pixel” mask was cosntructed by inspecting the bias frames. Five 10 minute exposures were collected before dew formed on the corrector element of the telescope. IRAF was used to process the data. The images were aligned and stacked. No flat frames were collected. A second order polynomial was fit to the background and subtracted.
100 dark frames and 100 bias frames were collected during poor weather a week earlier. A “bad-pixel” mask was cosntructed by inspecting the bias frames. Five 10 minute exposures were collected before dew formed on the corrector element of the telescope. IRAF was used to process the data. The images were aligned and stacked. No flat frames were collected. A second order polynomial was fit to the background and subtracted.
RAF was used to extract data on the stars in the image. The FWHM was determined to be 6 pixels. Worst-case seeing of 3” would produce a FWHM of 2 pixels. This indicates the telescope is not focused. In order to improce the resolution, the image was processed using the LUCY routine in IRAF. An unsaturated star near the nebula was chosen as the inital PSF.
The central stars are now clearly visible, as well as the stars in the edge of the ring and some ring detail. There are some artefacts around the brighter stars but the overall improvement is good. |
After posting the image on an imaging related newgroup, alt.binaries.pictures.astro, it was suggested that I increase the contrast in an attempt to detect a nearby galaxy, IC 1296. The image was re-oriented to roughly align the N-S and E-W axes and then submitted to the WCS-Fixer engine to generate plate-scale and orinetation. With the plate solution, an image of the same region was acquired from the Digital Sky Survey archive. The images were loaded into DS9, aligned, and contrast adjusted to bring out the faint features in each image. The galaxy can be detected in both images.
Even in light polluted skies, with tracking error, no flat fields, and small aperture, we can still get faint nebulae and galaxies.