Geek Out! How to Build Your Own Nova Delphini Light Curve

And now for something to appeal to your inner geek. Or, if  you’re like me, your outer geek. Many of you have been watching the new nova in Delphinus with the naked eye and binoculars since it burst onto the scene early Aug. 14. In a moment I’ll show how to turn your observations into a cool representation of the nova’s behavior over time.

Updated Nova Delphini 2013 chart using the latest visual magnitudes from the AAVSO showing stars around the nova to magnitude 7.1. Stellarium
Updated Nova Delphini 2013 chart using the latest visual magnitudes from the AAVSO showing stars around the nova to magnitude 7.1. Click for larger version. Stellarium

Where I live in northern Minnesota, we’ve had a lucky run of clear nights since the outburst began. Each night I’ve gone out with my 8×40 binoculars and star chart to estimate the nova’s brightness. The procedure is easy and straightforward. You find comparison stars near the nova with known magnitudes, then select one a little brighter and one a little fainter and interpolate between the two to arrive at the nova’s magnitude.

Estimating a star's magnitude by creating a sliding scale in your mind's eye between a stars that bracket the nova in brightness. Illustration: Bob King
Estimating a star’s magnitude by creating a sliding scale in your mind’s eye between stars that bracket the nova in brightness. Illustration: Bob King

For example, if the nova’s brightness lies halfway between the magnitude 4.8 and 5.7 stars it’s about magnitude 5.3. The next night you might notice it’s not exactly halfway but a tad brighter or closer to the 4.8 star. Then you’d measure 5.2. Remember that the smaller the number, the brighter the object. I’ve found that defocusing the stars into disks makes it a bit easier to estimate these differences.

In time, you’ll come up with a list of magnitudes or brightness estimates for Nova Delphini. Here’s mine to date:

* Aug. 14: 5.8
* Aug. 15: 4.9
* Aug. 16: 5.0
* Aug. 17: 5.0
* Aug. 18: 5.0
* Aug. 19: 5.2
* Aug. 20: 5.5

Template you can use to plot your own estimates of Nova Delphini 2013's night by night brightness through Sept. 11. Click for larger version.
Template you can use to plot your own estimates of Nova Delphini 2013’s night by night brightness through Sept. 11. Click for larger version.

So far just numbers, but there’s a way to turn this into a satisfying visual picture of the nova’s long-term behavior. Graph it! That’s what astronomers do, and they call it a light curve.

I dug around and came up with this very basic template. The horizontal or x-axis measures time in days, the vertical or y-axis plots the nova’s brightness measured in magnitudes. You can either right-click and save the image above or grab the higher-res version HERE.

I plotted my own brightness estimates of the nova using Photoshop Elements. You can do it on computer or with paper and pencil.
I plotted my own brightness estimates of the nova using Photoshop Elements. You can do it on computer or with paper and pencil.

Next, print out a copy and lay in your data points with pencil and ruler the old-fashioned way or use an imaging program like Photoshop or Paint to do the same on the computer. I use a very basic version of Photoshop Elements to plot my observations. Once your observations are marked, connect them to build your light curve.

Connecting the dots, we can start to see how the nova behaves over time. The sudden jump from obscurity as well as the brief plateau before fading are obvious.
Connecting the dots, we can start to see how the nova behaves over time. The sudden jump from obscurity as well as the brief plateau before fading are obvious.

Right away you’ll notice a few interesting things. The nova shot up from approximately 17th magnitude on Aug. 13 to 6.8 on Aug. 14 – a leap of more than 10 magnitudes, which translates to a nearly 10,000 fold increase in brightness.

I wasn’t able to see the Nova Del top out at around 4.4 magnitude – that happened when I was asleep the next morning – but I did catch it at 4.9. The next few days the nova hits a plateau followed by what appears for the moment like a steady decline in brightness. Will it rocket back up or continue to fade? That’s for you and your binoculars to find out the next clear night.

Official AAVSO light curve to date for Nova Delphini 2013 created using their light curve generator. The plot includes observations from many observers. Copyright: AAVSO
AAVSO light curve to date for Nova Delphini 2013 created using their light curve generator. The plot includes observations from many observers. Copyright: AAVSO

If you’d like to take the next step and contribute your observations for scientific use, head over to the AAVSO (American Assn. of Variable Star Observers) and become a member. Even if you don’t sign up, access to data, charts and light curves of novae and other variable stars is completely free.

Nova Sagittarii 2012 light curve. Notice the occasional plateaus as well as bumps in brightness as it faded back to minimum light. Credit: NASA
Nova Sagittarii 2012 light curve. Notice the occasional plateaus as well as bumps in brightness as it faded back to minimum light. Credit: NASA

I get a kick out of comparing my basic light curves with those created with thousands of observations contributed by hundreds of observers. The basic AAVSO curve looks all scrunched up for the moment because their time scale (x-axis) is much longer term than in my simple example. But guess what? You can change the scale using their light curve generator and open up the view a little more as I did in the curve above.

Light curve of V2467 Cygni, a nova that appeared in Cygnus in 2007. Credit: AAVSO
Light curve of V2467 Cygni, a nova that appeared in Cygnus in 2007. Credit: AAVSO

Here are a couple other typical novae light curves. By the time you’re done looking at the examples here as well as creating your own, you’ll gain a familiarity that may surprise you. Not only will be able to interpret trends in Nova Delphini’s brightness, but you’ll better understand the behavior of other variable stars at a glance. It’s as easy as connecting the dots.

 

Update on the Bright Nova Delphini 2013; Plus a Gallery of Images from our Readers

Since showing itself on August 14, 2013, a bright nova in the constellation Delphinus — now officially named Nova Delphini 2013 — has brightened even more. As of this writing, the nova is at magnitude 4.4 to 4.5, meaning that for the first time in years, there is a nova visible to the naked eye — if you have a dark enough sky. Even better, use binoculars or a telescope to see this “new star” in the sky.

The nova was discovered by Japanese amateur astronomer Koichi Itagak. When first spotted, it was at about magnitude 6, but has since brightened. Here’s the light curve of the nova from the AAVSO (American Association of Variable Star Observers) and they’ve also provided a binocular sequence chart, too.

How and where to see the new nova? Below is a great graphic showing exactly where to look in the sky. Additionally, we’ve got some great shots from Universe Today readers around the world who have managed to capture stunning shots of Nova Delpini 2013. You can see more graphics and more about the discovery of the nova on our original ‘breaking news’ article by Bob King.

The new nova is located in Delphinus alongside the familiar Summer Triangle outlined by Deneb, Vega and Altair. This map shows the sky looking high in the south for mid-northern latitudes around 10 p.m. local time in mid-August. The new object is ideally placed for viewing. Stellarium
The new nova is located in Delphinus alongside the familiar Summer Triangle outlined by Deneb, Vega and Altair. This map shows the sky looking high in the south for mid-northern latitudes around 10 p.m. local time in mid-August. The new object is ideally placed for viewing. Stellarium

If you aren’t able to see the nova for yourself, there are a few online observing options:

The Virtual Star Party team, led by UT’s publisher Fraser Cain, will try to get a view during the next VSP, at Sunday night on Google+ — usually at this time of year, about 10 pm EDT/0200 UTC on Monday mornings. If you’d like a notification for when it’s happening, make sure you subscribe to the Universe Today channel on YouTube.

The Virtual Telescope Project, based in Italy, will have an online observing session on August 19, 2013 at 20:00 UTC, and you can join astronomer Gianluca Masi at this link.

The Slooh online telescope had an observing session yesterday (which you can see here), and we’ll post an update if they plan any additional viewing sessions.

There’s no way to predict if the nova will remain bright for a few days more, and unfortunately the Moon is getting brighter and bigger in the sky (it will be full on August 20), so take the opportunity this weekend if you can to try and see the new nova.

Now, enjoy more images from Universe Today readers:

Nova Delphini 2013 from August 16, 2013 at 0846 UTC. Credit and copyright: Nick Rose.
Nova Delphini 2013 from August 16, 2013 at 0846 UTC. Credit and copyright: Nick Rose.
The bright nova in Delphinus when it was at magnitude 6.1 on August 14, 2013, as see from Yellow Springs, Ohio USA. Credit and copyright: John Chumack/Galactic Images.
The bright nova in Delphinus when it was at magnitude 6.1 on August 14, 2013, as see from Yellow Springs, Ohio USA. Credit and copyright: John Chumack/Galactic Images.
Proving that Nova Delphini 2013 is now a bright, naked-eye object, this fun image shows not only the nova, but the surrounding landscape in Sweden of the photographer, too. Credit and copyright: Göran Strand.
Proving that Nova Delphini 2013 is now a bright, naked-eye object, this fun image shows not only the nova, but the surrounding landscape in Sweden of the photographer, too. Credit and copyright: Göran Strand.
Nova Delphinii 2013 as seen on August 15, 2013. Credit and copyright: Andre van der Hoeven
Nova Delphinii 2013 as seen on August 15, 2013. Credit and copyright: Andre van der Hoeven
Nova in Delphinus from Ottawa, Canada on August 14, 2013. 13 second exposure under heavy light pollution with Nikon D80. Credit and copyright: Andrew Symes
Nova in Delphinus from Ottawa, Canada on August 14, 2013. 13 second exposure under heavy light pollution with Nikon D80. Credit and copyright: Andrew Symes
Image of Nova Delphini 2013, on 15 Aug. 2013, via the Virtual Telescope Project/Gianluca Masi.
Image of Nova Delphini 2013, on 15 Aug. 2013, via the Virtual Telescope Project/Gianluca Masi.
Annotated image of Nova Delphini 2013, as seen from Hawaii. Credit and copyright: Bryanstew on Flickr.
Annotated image of Nova Delphini 2013, as seen from Hawaii. Credit and copyright: Bryanstew on Flickr.

Ralf Vandebergh shared this video he was able to capture on his 10-year-old hand-held video camera to “demonstration of the brightness of the nova and what is possible with even 10 year old technique from hand.”