SoCal Astrophotography

Equipment

Celestron EdgeHD 9.25" · ZWO ASI294MM Pro · Baader Blue (B-CCD) 36 mm · Baader Green (G-CCD) 36 mm · Baader H-alpha 6.5nm (CMOS-Optimized) 36 mm · Baader Red (R-CCD) 36 mm · Baader UV/IR CUT Luminance (CMOS Optimized) 36 mm · iOptron CEM70 · Astro-Physics CCD Telecompressor (CCDT67) · Pegasus Astro FocusCube2 · Fabien Chéreau et al. Stellarium · Open PHD Guiding Project PHD2 · Pleiades Astrophoto PixInsight · Russell Croman Astrophotography BlurXTerminator · Russell Croman Astrophotography NoiseXTerminator · Russell Croman Astrophotography StarXTerminator · Serif Affinity Photo · Stefan Berg Nighttime Imaging 'N' Astronomy (N.I.N.A. / NINA) · Strasbourg astronomical Data Center Aladin Desktop

Integration

45h 2′

Reflection nebula vdB 133 presents as a multicolored vdB object. Its environs help explain its appearance. The reflection nebula, vdB 133 illuminating star is 44 Cyg - a spectral type F5, blue/white color. This star is about 4,240 light years distant (by parallax estimate) and is embedded within the vdB 133 nebulosity. This places the nebula at about the same distance. LBN 219 in the lower part of the frame has a high Ha content that came through in the Ha exposures. The star HD195407 is a bright energetic spectral type O2 star - which would qualify for an ionization star for the LBN 219 Ha emission. This star is about 4,080 light years distant (parallax estimate) - about the same distance as star 44 Cyg (vdB 133). The vdB catalog lists vdB 133 region absorption as ‘Strong’. HD195407 would ionize Hydrogen present there. So the Ha emission is at least line of sight with vdB 133 and quite possibly at a similar distance as vdB 133 (4080 - 4240 light years). The vdB 133 reflection nebula color likely has various components: 1) true reflection from star 44 Cyg (blue/white), 2) coincident Ha emission content (red) from surrounding field / LBN 219, 3) strong absorption environment (ISM) where dust can reflect neutral brown color while absorbing blue light. These components give vdB 133 much of it's color diversity. Also, LBN 218 is seemingly coincident with vdB 133; both have similar color and brightness descriptions in their respective catalogs and coordinates are very similar as well. It is likely that the same nebulous structure is identified by both of these catalog identifiers, however the Simbad astronomical data base does not list these as co-identifiers. vdB objects are generally listed under their illuminating stars in Simbad. About Sidney van den Bergh’s 1966 publication: It is interesting to see the narrative of Sidney van den Bergh’s 1966 publication of his study and the vdB catalog itself. The catalog in table form is available on Vizier at vdB Table I ; but the publication itself is more interesting to read. The van den Bergh narrative of his study is fascinating - A Study of Reflection Nebulae . (caution - this link may time out and need one or more refreshes - but if that fails a scanned image version is HERE ). Specific criteria are listed for the inclusion of ‘reflection nebula’ are given in the narrative: - There is an associated illuminating star - it can be embedded in or outside of the nebula. - Nebula is present on both red and blue plates of the Palomar Sky Survey - Exclusively emission nebulae were excluded on the basis of their colors and morphology - Other nebulae lacking a clear illuminating star (including high latitude cirrus) were excluded About 170 candidates met these restrictions. 158 candidates made the catalog. The van den Bergh study found that vdB nebula color was predominantly dependent on the spectral type of the illuminating star: vdB 133 star’s spectral type is F5 and is listed as moderately blue (mB) - halfway between the F0 / G0 on the scale. A majority of the vdB objects fall into the [vB, B, mB, I] color category - illuminated by spectral type B or A stars. vdB 133 falls in the minority of vdB nebulae not illuminated by spectral type B or A - a minority colored from moderately blue to very red (vR). One eye popping discussion in the 1966 vdB publication was the reference to IFN. The section on ‘Illuminated Clouds at High Latitudes’ discussed these nebulae that are not included in the vdB catalog since they lacked an illuminating star. But instead are illuminated by integrated light of galactic disk stars. [The study data] “strongly suggest that the faintly luminous clouds, which are observed at intermediate and high galactic latitudes, are illuminated by the integrated light of the Milky Way. This conclusion is supported by the observed average color index P-V≈0.7 which agrees rather well with the value P-V=0.89 which Elsässer and Haug find for the integrated color of the Milky Way.” So in the Steve Mandel study (2004) of high galactic cirrus clouds, he designated some of these clouds as “Integrated Flux Nebula” (IFN) - lit by the integrated flux of Milky Way stars at the galactic disk. This was hinted at by van den Bergh back in his 1966 publication!