Double Cluster (NGC 884 and 869)

Jan 2013

The Double Cluster are two open clusters on the border between Perseus and Cassiopeia. This image was taken using the Narrowband for Stars Technique with (V,Y, and NIR). See the link for more information.

click for a full size (9"/pixel) image

Annotated Map

click for full size image

Processing Details

Due to weather and the season I could only collect a limited number of images. Fortunately the object is bright (which requires less stretching) and the weather was cold so my camera could run fairly cool.

Filter	Exposures
Strömgren sV	600s x 20
Strömgren sYel	600s x 12
NIR	600s x 8

That is only part of the story. As described in the NB4Stars page, the raw images have to be combined to form an RGB image. I used the following expressions in PixInsight PixelMath.

RED = "NIR_600x8*.33+sYel_600x12*.2";

GREEN = "sYel_600x12";

BLUE = "sV_600x20+sYel_600x12*.25";

From that point it was just normal processing. Since these were just stars I chose to not aggressively stretch the final image.

Area Map of Double Cluster

Area Map
9 PM Jan 2

Copyrights for Photos

Except as noted, all work on this site by Robert J. Hawley is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License. This permits the non commercial use of the material on this site, either in whole or in part, in other works provided that I am credited for the work.