https://www.itelescope.net

We will use iTelescope to take pictures of deep-sky objects. Browse their website using the link given above.

The very first thing an astronomer does as part of her observation is to select an ‘interesting’ astronomical object. We will do the same. What do I mean by ‘interesting’? Well, you will decide that by yourself. I can only suggest 3 criteria for finding something interesting: truth, beauty and order. Select something orderly and beautiful and something that can help us get closer to the truth about our place in the universe.

Each group has to use the iTelescope Planner for selecting at least 3 objects of interest. Go to the linked website and select Utah Desert Remote Observatories as your ‘Site,’ and give the date of a specific session of the semester.

Remember that you have to give the time in the current time of Utah, USA, that is MDT or ‘Mountain Daylight Time.’ MDT is exactly 12 hours behind us. When it is 10 am for us, it is 10 pm the day before in Utah now. So if you want to do the observation on 16 October, 10 am, then you have to select 15 October in the website.

Next, select a few types of object that you are interested in. I suggest you go for galaxies, bright nebulae, dark nebulae, globular clusters and supernova remnants, for now. Select to show 50 results per page and click on the ‘Search’ button.

You will see a list of observable astronomical objects with their name, preview picture; and details about their position, brightness (magnitude), size, and the distance of the object from the moon during the selected day. You will also find the visibility of the object on the fourth column.

The visibility has three numbers, the first one is the rising time, the second one the transit time, and the last one the setting time. The difference between the rising and setting time is usually around twelve hours, and the transit occurs when the object is right above our head, when the object reaches the highest position in the sky on a given night.

It is always better to observe an object around the time of transit. Not exactly at the time of the transit, but around that time. If the difference between rising and setting time is twelve hours, then it takes approximately six hours for an object to reach the transit position after its rise. So, for example, if I see that the Andromeda galaxy will transit at 12 am, 16 Oct, then it must have risen at around 6 pm, six hours earlier. If it was near the horizon six hours ago, then it would be halfway toward its transit around 3 hours ago, meaning at around 9 pm.

The rising, setting and transiting can be explained using a protractor or goniometer shown above. It has 180 degrees marked from left to right and right to left. If we are facing toward north, east would be to the right and west to the left. There are 180 degrees from right to left, east to west.

If the observer is located at the center of the horizontal line, then the object is toward 0 degree during the time of rising, toward 90 degrees during the transiting time, and toward 180 degrees during the setting time. An astronomical object might go up or down by an angle of around 15 degrees in one hour, so a total of 180 degrees in 12 hours. The actual time taken depends on many other things which we will skip for now.

We can observe an object for around 4 hours on either side of its transit. If Andromeda transits, reaches its highest point, at 12 am, then we can observe it from 10 pm to 2 am, which suits us very well because our classes are typically from 10 am to 11 am.