Urban Astronomy: Stargazing In City

Nova Delphini 2013

2013-08-20T22:34:00.000+03:00

Yesterday, i saw an alert notice about a naked eye nova in Delphinus. AAVSO also prepared a binocular chart for Nova Del 2013. It is currently at fifth magnitude so one needs at least binoculars to see from a city. Tonight, i checked the nova and found easily even under heavy light pollution and near full moon.

Beautiful Trio

2013-05-26T23:24:00.000+03:00

Yesterday, i saw Venus after sunset. Although there was no other object visible to naked eye, my 10x50 binocular revealed Jupiter and Mercury. As sky darkens, Jupiter got visible to naked eye but i needed to stop observation to take care of my kid. After kid slept, i checked Sky and Telescope's May and June 2013 issues. Especially, June 2013 issue has an article about seeing these three object in daylight. I decided to prepare for next evening.
Today, i prepared my EOS 1100D camera and binoculars before sunset. As Sun sets, i scanned the sky with my binoculars. About 5-10 minutes after sunset i saw Venus. A few minutes later Jupiter revealed. I needed to wait for a few more minutes for Mercury. I was only able to see Venus with naked eye then. About 30-40 minutes after sunset, all three planets were easy to see with naked eye although their altitudes were lower than 10 degrees. I took many shots, one of which is this:

I catched Jupiter just before hiding behind the building. I will continue to observe the planets, their relative location changes very fast indeed.

AAVSO Binocular Program

2013-01-09T22:37:00.001+02:00

AAVSO has a new program for binocular observers. AAVSO Binocular Program consists of 153 stars and most of the stars have minimum brightness of 9.5 magnitude. Observers in cities cannot see that faint stars but the list contains many brighter stars as well. AAVSO also updated their charting tool VSP (Variable Star Plotter) so that you can create special binocular charts for these stars.

Astrophotography in city with EOS 1100D

2012-12-30T22:08:00.001+02:00

Last month I got a Canon EOS 1100D as a birthday present. In additon to the kit lens, i bought a Canon EF 50mm f/1.8 II. The main purpose to buy this lens was to take indoor shots of my baby but of course i was also curious about astrophotography with this equipment.

I started with basic settings (wide open aperture, highest ISO and 30 sec exposure) but the light pollution was so high (limiting magnitude around 3.5) that all i got a was a pinkish, saturated picture without any star. I played with the setings and got best shots with 3-4 sec exposure, around f/4 aperture and 800 ISO. Here is a shot of Orion, Taurus and Jupiter at 18mm:

Then i switched to 50mm f:1.8 lens; using similar settings (4sec, f/4, 1600 ISO), i shot in Orion Nebula (M42) direction and i got following 100% crop shot of Sword of Orion region:

Open star cluster NGC1981 and M42 can be seen as well as stars up to 9th magnitude brightness. Here is the chart of the region created by Cartes du Ciel software (limiting magnitude is 8.8):

After this 100% cropped picture of Sword of Orion, I got curious about large deep sky objects like M31 (Andromeda Galaxy) or M45 (Pleiades). Pleiades was in a convenient position so i tried M45 and got following shot:

The object was close to edge of the frame so i think that's why there are not 9th magnitude stars in this shot (vignetting). M31 direction was obstructed but i tried M44 and surprisingly the cluster was resolved fine.

Finally, while checking my pictures, i have seen that there are two dots near Jupiter. Here you see 100% crop and 2x magnified photos as well as Jupiter's satellites' position according to Cartes du Ciel:

As you see, Europa and Callisto are captured. Ganymede can be more distant than Europa so it is well within capability of the camera. It seems that Io cannot be captured with these settings. However, as you see Jupiter is over exposed and satellites are bright enough to be captured at 1 or 2 stops lower exposure so I will try Io when it is farthest from Jupiter with less exposure.

These shots show that under heavy light pollution, you can capture 5 magnitudes (100 times) fainter stars with EOS1100D DSLR camera using humble settings (4 sec shutter speed, f/4 aperture, 800 ISO) using a 100$ lens. If you use 100% crops you can resolve brightest deep sky objects too.

Venus Transit Report

2012-06-06T22:55:00.000+03:00

Long awaited Venus transit has passed. Here is my Venus transit story:

According to long term climate data, here in Ankara, expected cloud coverage was around 50% during transit. Therefore, i started checking the forecast since last days of May. Until 4th June, it was usually clear and the forecasts say nothing bad about the day of the transit. On 4th June, forecast said that there will be thunderstorm on 6th June starting late morning. Here, i would be able to see at most the last two and a half hours of the transit after sunrise on 6th June so i got shocked. I checked several online sources and all predicted that clouds will increase between 7AM and 8AM (transit ends at around 7:55). I had excitement and hope but i also thought that it was possible that i would not witness this event at all. I checked the sky until sleep, it was clear.
I woke up at 4:38AM but was not able to get up until 5:20 (exactly at sunrise), i moved to my east-looking window and understood that the Sun would rise enough in 10 minutes but there was dark clouds near horizon and upcoming clouds do not look promising.

Dark clouds covering my eastern horizon and upcoming clouds do not look promising

So first i had my breakfast and checked my equipment, camera batteries and memory. My equipment list was short actually: My 7 years old Sony DSC-H1 digital camera, home-made solar filter using Baader Planetarium filter sheet and solar viewing googles (!) from Bilim ve Teknik magazine.

My humble setup

At around 6AM, the Sun started showing itself and first i tried to see Venus with filter and surprisingly Venus was very obvious and easy to see. I called my wife who was just awake, she came and her jaws dropped while witnessing this rare event . I started taking shots and the weather got clear, some of my shots are here:

As you see some sunspots can also be seen in the picture but Venus is much larger and darker.

During that time, i briefly tried projecting the Sun with binoculars but the result was not satisfying.
As time passed, clouds started to accumulate and i realized that third contact and maybe fourth contact would be obscured by clouds. After the Sun is blocked, i went to another room to upload pictures from camera to my computer. Then i moved back to my east looking room and have seen that the Sun was visible but it was agained blocked by clouds before even turning my camera on. I checked my watch, it was almost third contact time. The part of the transit that i don't want to miss was around third contact because i wanted to see the black drop effect. I have heard it maybe 20 years ago and was very curious about it for many years so it had some special meaning to me. And i missed this opportunity while sitting in front of my laptop. A lesson; never leave observation, anything can happen anytime.
Then i found some opportunities to get some shots between third and forth contacts. Usually there were some clouds as you see on the pictures but anyway i am OK with them. After third contact, I no longer could see Venus with filter so it seems that during transit, Venus' size was almost at my naked eye resolution limit but due to high contrast i was able to see it that easy.

Only a few seconds before fourth contact i got following shot to say goodbye to Venus.

To sum up, it was really a great experience, even better than my expectations. I want to conclude with my wife's words "Seeing the transit was very exciting. When i see a Venus transit picture, I remember seeing Venus moving on the Sun. Without seeing this event by myself, the pictures would not have any meaning to me"

Ready for Venus Transit?

2012-06-05T21:21:00.001+03:00

After getting baby, i stopped stargazing and blogging. But transit of Venus is so important that i made some preparation to observe and photo that rare event. I made some trial shots of the Sun when it was at almost same altitude as at the last phases (only visible part of transit from here) of transit. It seems that photo resolution is enough to show Venus.

The weather forecast says that it will be partly cloudy in the morning, i hope i can see the transit. By the way, Astronomical League and NASA can give you certificates for observing the transit. For detailed information, visit this page. I hope clear sky to everybody observing the transit.

Urban Binocular Variable Star List

2012-02-18T19:20:00.001+02:00

A few months ago, I decided to create a list of variable stars observable with my binoculars from city. I started with downloading data for variable stars reaching at least 7.5 magnitude brightness from VSX variable star catalog as explained here. After downloading the data, i filtered out supernovae and novae except recurrent novae. Then removed variable stars with magnitude change less than 0.4. Afterwards i excluded all stars without "V" or photographic magnitude data. Finally i removed suspected variables.
The resulting list can be found here.
The list contains data for 638 variable stars and i hope it helps you to find variable stars to observe.

Baader Astro Solar Filter

2012-02-12T08:53:00.000+02:00

2 weeks ago, I ordered Baader Astro Solar Film from Baader Planetarium. My main purpose was to observe Venus transit on 5-6th June 2012. It arrived as a A4 size sheet of solar filter placed in a hard envelope. I built the filter as explained here but the resulting filter looked rudimentary because of my lack of hand skill. Next morning i could not wait to take trial shots with the filter and found out that although the filter does not look promising, the image quality was nice. For example, following picture was taken on 11th February 2012 morning and you can see 2 close sunspot sharing same sunspot number.

Sony DSC-H1, fl:432mm (35mm equivalent), f/5.6, 1/500s, ISO 64, ND5 Solar filter

The sunspots seen on the picture are smaller than Venus' size during transit so it seems that i can take Venus transit shots with this filter if weather permits. This year Sun is quite active so i wish i can take better sunspot shots this year.

Go Voyager 1

2012-01-28T21:11:00.000+02:00

According to last Voyager Mission Status Report, a heater on Voyager 1 spacecraft was turned off in order to reduce power consumption of the spacecraft. The good news is, the aim of reducing power consumption is to extend the mission to 2025.

Special Astronomical Events in 2012

2012-01-27T19:46:00.000+02:00

I checked NASA Space Calendar for important astronomical event of 2012 and marked them on my calendar. This year's top event is Transit of Venus on 5th-6th June. Next transit of Venus is 105 years later so this will be our last opportunity to see that event. Sky and Telescope has an article about the event in January 2012 issue and there is an online article on their website.
There will be 2 solar and 2 lunar eclipses in 2012.
On 20th May, there will be an annular eclipse visible from China, Japan, Pasific and Western United States. For details check here.
On 4th June, there will be a partial lunar eclipse visible from Pasific Ocean, most of Americas and Eastern Asia. For details check here.
On 13th November, there will be a total solar eclipse visible from Austraila and Southern Pasific. For details check here.
On 28th November, there will be a partial lunar eclipse visible from Asia, Australia, Europe, Eastern Africa and North America. For details check here.
2012 is a Mars opposition year, this opposition will be on 3rd March.
There will be a close opposition of asteroid Eros on 7th February. It will reach 8.6 magnitude in those days and it will not be any closer until 2056. For details check here.

M101 and Supernova 2011fe

2012-01-06T07:00:00.000+02:00

Even after a long delay, i am not writing about what i promised. I had to stop blogging for a few months and i believe that i will orgsnize what i have and continue with variable star observing.
During my absence, one of the most interesting astronomical events was the supernova in M101 galaxy, namely Supernova 2011fe. According to AAVSO, it is "The brightest supernova in the last 20 years!" reaching 9.5 magnitude. Because M101 is a very popular photographic and visual target, the supernova has been detected in very early stages of explosion and examined very thoroughly.
It is very difficult to see M101 galaxy in a city due to its very low surface brightness but the supernova (because of being a point source) was much easier to see.
I observed the supernova when it was near 10.0 magnitude and it was fairly easy to see, actually more difficult thing was to starhop to the location of the object. Of course the galaxy was not there even though its total brightness was about 3 magnitudes more.

Variable Star Observing In City: Introduction

2011-06-24T15:04:00.000+03:00

Variable star observing is known to be one of the most accessible ways of contributing to science for an amateur astronomer. When I first learnt variable star observing, it seemed attractive but I scared to “ruin” collected scientific data by my “incorrect” brightness estimates. Therefore, I decided not to do variable star observing and concentrated only on leisure activities like deep sky or planetary observation. In 2009, I encountered an article in Sky and Telescope magazine about Epsilon Auriage and then heard 10 star program. They changed my opinion about variable star observing.

10 star program is a variable star observation program about 10 bright variable stars. They are all naked eye stars but in city most of them may require binoculars especially at minimum brightness. The tutorial is aimed to train the novice variable star observers through 10 easy to find and observe variable stars with particular emphasis on Epsilon Aurigae. It briefly explains how to estimate brightness of stars and how to use variable star charts.

If 10 stars do not seem enough to you (like me), you can continue with AAVSO Visual Observing Manual and vast information in AAVSO website. “Observers” section in AAVSO website provides links to the list of stars easy to observe, 10 star tutorial, WebObs (online observation entry page), VSP (chart generation tool), recent observations of stars and observing sections’ pages. After making your observations, you need to record them. The easiest way is using WebObs through its basic interface; however, before that you need to get observer initials from “Observers” page. Observer initial is the unique code of an observer and your observations are tagged with your initials. After getting your initials, username and password, you are ready to log your observation.
In the next post, we will explore variable star observing in city with binoculars.

13mm Nagler Type 6: First Light

2011-06-22T21:32:00.002+03:00

In his book The Urban Astronomer's Guide: A Walking Tour of the Cosmos for City Sky Watchers (Patrick Moore's Practical Astronomy Series), Rod Mollise says that wide field eyepieces will help in deep sky observing by providing enough field of view while keeping magnification high. It is well known that high magnification darkens background so contrast between object and the light polluted background improves thus the observer can see the object easier.
As a stargazer observing under heavy light pollution, I followed his advice and decided to get a 82-degree eyepiece. I made an extensive research on optical performance and availability of the alternatives and decided to get 13mm Nagler Type 6. 13mm Nagler gives 94x magnification (a very useful magnification) on my 8 inch dobsonian with apparent field of view of 52 arcminutes. I bought it from amazon.com at about 220$.
The eyepiece is larger than my 26mm Meade Series 4000 Super Plossl but smaller than 32mm Celestron Plossl. Physical quality was very good and the dust caps fit securely. The first look was very pleasant though not stunning (i expected more immerse effect) and the large field of view was really obvious. I compared the view with 26mm Plossl and 2x Barlow and of course Nagler's image quality was better. But this comparison showed me a shortcoming of Nagler compared to Plossl: Lack of eyecups. I find it more difficult to use Nagler after placing my eyes on the eyecups of the Plossl. The Nagler is still pleasant to use though and when i switched back to Plossl from Nagler, i felt as if i was looking through a narrow pipe. I have not looked to a planet or the Moon with my new eyepiece and i am looking forward to observe them and report Nagler's performance. I am glad that i got this eyepiece and hope to enjoy it for many years.