Collecting  Photons

North is to the right. Wide field: 1600x1149

Objects:             A dust field with two bright reflection nebulae with contrasting colours: VdB 9 on the left and VdB 7 on the right. LDN 1355, LDN 1357 and LDN 1358.

Constellation:     Cassiopeia

Coordinates of field center (J2000): 2h 52m 10s; +69° 24'

Notes: VdB 7 is a bit mysterious: it is apparently associated to the bright blue star (RZ Cassiopeia, A3V, 250 LY), however the nebula appears deeply red. Considering that the star associated with VdB 9 is much farther away (SU Cassiopeia, F5, 1412 LY) one would think that RZ is only apparently associated to the nebular field and that it does not contribute to the illumination of the reflection nebula. The field is covered by thin layers of dust that, in places are extremely dense.

Telescope and camera: ASA 10', f 3.6; TEC 140, f 7.2, SBIG STL 11000.

Exposure: ASA: L 15x10'; R 15x10'; G 12x8'; B 11x10'. TEC: L 25x10'; R 13x10'; G 9x8'; B 7x10'. About 16 hrs total.

Date: four nights on September-October 2011.

Software used: acquisition, CCDsoft, FocusMax, The Sky VI. Calibration; registration and stacking: CCDstack, Registar; processing: PixInsight 1.7, Photoshop CS3. 

Processing notes: Registar was crucial to allign the ASA and TEC images, since a simple affine transformation is not sufficient for a correct registration. PIP processor in PixInsight. A bit of star erosion to abate their luminosity and recover the colour in the bright core.

Copyright © 2011 by Gimmi Ratto. (October 30, 2011)