Hi,

Just a quick update on my new website Starobserver.eu. I added another sketch to the open cluster section. Last winter I observed NGC 2420 in Gemini. This little cluster lies in the neighbourhood of the Eskimo Nebula, For a detailed observing report, some info on the discovery of this cluster, a finder chart and other interesting things on NGC 2420, please follow this link to NGC 2420 on StarObserver.eu

Enjoy!

eta Persei is a bright double star, placed within a striking asterism. When I was writing my notes on this double, I found out the collecting the right data on individual stars is sometimes much more complicated than you think. I got some help from an Austrian astro-photograpeher, Peter Wienerroither. His image of eta Persei was a great help identifying all the components of eta Persei. To read the full report, just follow this link to StarObserver.

NGC 6910, a small and compact open cluster in Cygnus. When observing this open cluster you see bright yellow stars, that are in fact B-stars. So they should appear white. What causes the yellowish appearance is explained in this article, where I got some great help from Professor James Kaler, author of some of the best books on stars, and Dr. Franz Gruber, who sent me a few magnificent deepsky images of the Cygnus area to illustrate the high degree of nebulosity in the Cygnus area. To read the full story, and have a look at the wonderful images of Dr. Franz Gruber, follow this link to StarObserver.eu




Image by Dr. Franz Gruber

Today I launched my new website, Star Observer, a website dedicated to the observation of stars and open clusters. I created this website to have a more structured way to present my observing reports from my favorite objects: stars and open clusters. At the core of Star Observer you will find a new and growing collection of visual observing reports. There is a separate page for every object observed. On an object's page you will find my personal observing report, a sketch (or image) and some notes and background information about the object. The observing reports can be found in the top bar menu under "Single and multiple stars" and "Open clusters". In the section "observing stars" you will find some information about the equipment and resources I use for planning, executing and evaluating my observations.

In the future new observing reports will be added on a regular bases. I am also planning to publish a few articles about stars and clusters, and the method I developed for planning, executing and evaluating / publishing my observations.

You can navigate through StarObserver.eu using the different menus or the sitemap. If you have any questions or suggestions, please feel free to contact me, using the contact form.
Updates on StarObserver.eu will be announced in this blog. Follow this link to go to the homepage of Star Observer.


Clear skies

Math Heijen

Hi,

It's been a long time since you heard from me, but during the last few months I've been working on a new website dedicated to the observing of stars and star clusters. It will take a little while before it will go online, but I will let you know! In the meantime I'm working on the design and content for this new site, and every now and again I look outside, and wow, in the last week of January Venus and the Moon were lined up in the evening sky. Hope you like the images. Please click to enlarge.

Hi,

Last week I shot a few images with my Canon Powershot handheld at the 85mm Zeiss Diascope. Here's a nice sample!


Click to enlarge

At the moment I'm testing my new camera, the DMK 21AF04 AS. I first tried the camera on the Coronado PST, and I was surprised by the result. The first image is a typical frame I selected from the 1-minute movie I shot from a prominence. The second image shows the stacked (600 frames) and processed version.






I will inform you about the equipment set-up and the stacking/processing software in the near future. Right now I'm busy reading the software manuals and experimenting with the few movies I recorded. In the end this monochrome camera will be used to shoot detailed images of the Moon, the Sun in combination with the Baader Herschel Prism/Continuum filter and the Sun in H-Alpha with the Coronado PST. I will keep you updated!

I would like to thank Jim Kaler (Prof. Emeritus of Astronomy, University of Illinois), for helping me with my “spectral riddle” in NGC 6910, the Rocking Horse cluster. Here’s why the B1 supergiant looks yellow visually instead of bluish-white what you would expect from a B-type star.

As you know it is in the middle of Cygnus, near Gamma Cygni, not far off the galactic plane (you can see my wide angle picture at http://www.astro.uiuc.edu/~kaler/sow/sadr.html).  As such it is subject to a great deal of interstellar extinction and reddening from interstellar dust. The dust selectively absorbs and scatters blue light (roughly 1/wavelength), so when you look at a star thru dust it will appear redder than it really is (basically the same reason the sun is reddened at sunset).  The intrinsic B-V color of a B1.5 Ia supergiant is -0.2. The observed color is 0.83, about the color of a K0 dwarf or a G5 giant, so the star appears yellowish to the eye.

The whole cluster is highly reddened in fact by about the same amount. The “color excess” (E) is the observed minus true color, which is about 1.0 for this cluster. The absorption at V is usually taken as 3.2E, so Av (abs at V) is 3 magnitudes. If there were not dust, a 7th magnitude star would appear 4th magnitude, and the cluster would be visible to the naked eye. Good observing on your part to notice that. You can see the effect in many other distant clusters near the galactic plane.

Jim Kaler

Thanks again!