SDAC Solar Image


Aurora Borealis


Article 2

Andy Devey's observing tips - How to orientate your Hydrogen Alpha image.

When looking through your PST or other Hydrogen Alpha telescope the prominences etc that you see will vary in rotation depending on what time of year and what time of day you are observing. The easiest way to check and correctly align these features is to use the internet and check the NSO/GONG H Alpha Network Monitor or try this link to access the same data. Here is an alternative link that you can use to orientate your image. This displays a page containing 6 separate images from the ground based observatories that contribute to this 24-hour solar-monitoring program. They are Learmonth, Udaipur, El Teide, Cerro Tololo, Big Bear and Mauna Loa Solar Observatories. If you click on the link above you will be able to access this data base. All you then need to do is set your camera into the eyepiece holder of your telescope watch the image on your monitor/lap top and then twist your camera/webcam and set your image to that same orientation as displayed on NSO/GONG.

Remember if necessary you can also rotate or flip your images later when you are processing your images in Photoshop if needed?

Further if you click onto the movie camera symbol at the bottom of any of the images you will see the sequence run for the last few hours. this will help you chose the most dynamic target that you could consider for an interesting animation run.

Solar events can be very fast-moving and over in just a few minutes, so speed of set up is vital. On occasions I just stick my DMK21 straight into my PST on the alt/azimuth mount and turn it to roughly the right orientation. I use the hand wheels to move the object of interest to the center of the frame and just let it drift for say 300 frames. You will obviously get field rotation when on this type of mount. This can be corrected later in Photoshop CS5. I check the last image over the first and click [Image], [Image rotation] and then [arbitrary] to see how much the last frame rotated. If you have say 20 evenly spaced frames then rotate each frame by that cumulative 1/20th amount before animating. Here is an example of a huge limb blast from the 3 December 2011 I have included the raw GIF and then the image rotation corrected GIF. These were captured with the PST at 0.8m focal length. I have corrected for field rotation and also turned the image through 20 degrees to get the correct limb orientation.

3 December 2012 limb ejection

If you want to check on the magnitude of the flare that you have just captured then click on this NOAA  link or the NOAA updated link to get its precise magnitude. Then click on the GOES Solar X-ray flux graph, the scale on the right hand side of the graph will let you measure the magnitude of that flare! If you are a few days out there is a link to the events of the last 60 days or the historical link back to 1966. Here is a reference page to show you how to estimate the scale of that flare.


How to watch for solar flares/events

I just open the GONG live image on one side of my laptop screen and the NOAA graph on other to monitor the almost live image.

images/stories/watching for solar activity small.jpg

Happy hunting.