Shortly after my last post I observed the nova again. Within 24 hours it has dropped by a full magnitude after peaking at 5.7, a little higher than my binocular estimate of 5.8 from last night.
My two observations are in purple, as usual, with the observation an hour ago under the cross-hairs.
A “happy snap” (with iPhone) of the sky over my backyard rooftop, with Luna peeping through cloud. The nova’s location is behind me from this vantage point.
After being away for a week and a cloudy sky on Sunday, I caught my first glimpse of Nova Carinae 2018 (ASASSN-18fv) in 7×50 binoculars minutes before the sky started clouding out.
I estimated it to be 5.8 (purple, at top right) at just after 11pm Adelaide time.
Note also the upward trend-line.
I had hoped to subsequently image the nova to carry out DSLR photometry for better accuracy but that didn’t pan out due to cloud.
At the time of submission to AAVSO the last observation before mine was 6.5, several hours earlier. Since then, others have submitted observations up to 5.9. So, I appear to have caught Nova Car 2018 on the rise and at its peak so far.
Nova Car 2018 or ASASSN-18fv was discovered by the ASAS Supernova network on March 21st and has so far reached around magnitude 6.5 from a progenitor magnitude of 19.9 within a couple of days.
Below is a Stellarium view of the location of ASASSN-18fv, very close to the 5.1 magnitude comparison star near the Eta Carina nebula and star, a variable whose brightness I often estimate.
A binocular finder chart with a slightly different orientation from the Stellarium screenshot is shown below:
This is a crowded area of the sky, and being so close to the 5.1 star, it may be tricky in a low power binocular field.
Rob Kaufman posted this image of the nova, with yet another different orientation:
I have not yet had the opportunity to observe the nova; hopefully in a couple of days.
The AAVSO alert notice has more details.
AAVSO alert notice 613 for the nova in Circinus requests visual, DSLR, CCD and spectroscopic observations, with multiple observations each night if possible, in support of the Fermi Gamma-ray Space Telescope’s observations that are currently underway:
Target-of-opportunity observations requested by Dr. Mukai are taking place now through February 6 UT with the NASA Fermi Gamma-ray Space Telescope. To support these observations, observers are asked to make several observations per night.
I’m processing DSLR observations of the nova from last night and plan to continue observing over the next few nights. Its visual magnitude is currently at around 7.2.
Here’s a spectrum taken by Rob Kaufman on January 31:
Adelaide was largely clouded out for the eclipse but the cloud thinned at times well enough to get some reasonable images, especially after midnight. Taking more than 100 images also helped.
I used a Canon 1100D at the prime focus of my 8″ Schmidt-Cassegrain Alt-Az (Meade LX-90) telescope.
Here are some images I thought were interesting enough to show. These are straight off the camera with no processing except RAW to JPEG conversion.
In my last post on January 20 about Nova Mus 2018, I said that another southern nova had been discovered, this one by John Seach in the early hours of January 19 in the constellation of Circinus, near alpha and beta Centauri. That post also showed a Stellarium context screenshot and pointed to an AAVSO finder chart.
This nova has slowly been on the rise for the last several days from around magnitude 8.5 to 6.3 by January 27.
The following 15 second DSLR images I took on Jan 22, 23, 26 and 27 show the nova brightening over time:
If the images seem out of focus, that’s because they are. They were used for photometry rather than with the intention of being pretty; use of defocus is part of the procedure. See this talk I gave about DSLR photometry in 2015 for more detail. There’s some positional differences between frames, reflecting the difference in observation time from night to night.
The light curve below shows visual, Johnson V, and Tri-Color Green (DSLR) observations from January 19 to 28; mine are in purple. I’ve also submitted observations in blue and red bands.
This light curve doesn’t appear to show a simple linear increase, so it will be interesting to see where the rise stops.
Rob Kaufman (discoverer of Nova Mus 2018) said that a low resolution spectrum he took on January 26 was essentially featureless.
The sky is largely clouded out tonight here in Adelaide at the end of a hot day (42° C), but I just caught a quick glimpse of the nova in 7×50 binoculars, but wasn’t able to check against comparison stars. It’s around the same magnitude as last night though. I’ll carry out more DSLR photometry as soon as I can.
In the meantime I have two more nights of Nova Mus 2018 (currently on the decline) DSLR images to process. I’ll write an update post for that nova too.
It’s been several days since the nova in Musca was found by Rob Kaufman. The alert notice was sent out by AAVSO on January 16.
Below is the green filter channel of a DSLR image I took around midnight on January 17. The nova is shown via red markers with a faint satellite trail at upper right. Compare this with the narrow field Stellarium screenshot in my last post.
That was one of 20 images used for photometry of the nova that night. I’ve repeated this on two other nights since submitting untransformed green (visual wavelength), blue and red band observations.
My visual band (binocular and DSLR photometry) observations are shown below in purple alongside visual band contributions from others:
A polynomial fit makes the emerging pattern a little more obvious (if exaggerated in parts); up and down from night to night as is common with novae.
This morning another southern nova was discovered in the constellation Circinus (near Alpha Centauri) by John Seach in NSW at magnitude 9.1. John also discovered a bright nova in Centaurus in 2013. I have not been able to observe this yet due to cloudy conditions tonight.
Here’s a Stellarium screenshot of this latest nova’s location:
The AAVSO finder chart I will be using initially is this: 
Rob Kaufman in Victoria discovered a possible nova (PNV J11261220-6531086) near the Southern Cross (Crux) in the constellation of Musca on January 14 2018. All novae start out having the designation PNV or possible nova.
Rob’s discovery visual estimate was magnitude 7. I estimated it tonight with 7×50 binoculars at magnitude 6.7 relative to magnitude 6.4 and 7.1 comparison stars.
This context screenshot from Stellarium shows the nova’s location (cross-hairs at upper middle of image) relative to familiar stellar sign posts, including Crux and Alpha Muscae at 10pm Adelaide time (AEDT).
The next shows a narrower field of view with the nova at right of the helpful triangular, A-shaped asterism.
Here’s a 10º finder chart from AAVSO
and an 8º finder chart with the orientation closer to that of the sky around tonight’s observation time. The two comparison stars I used are circled in red.
After submitting my observation tonight to AAVSO I noticed that since Rob’s discovery observation, only two have been submitted other than mine:
What I love about such transients, is their spectacular brightness rise and unpredictability.
Initial spectroscopy by Rob indicates a classical nova. I’d expect to see more amateur spectroscopy of this object in the near future.
Will it become visible to the naked eye like the similarly southern and close-to-Crux V1369 Cen did in 2013 (peaking at around magnitude 3.4)? One never knows with these things but it’s worth noting, as per the CBAT transient report page, ASAS-SN observations suggest the nova may actually have started in the first few days of January. If so, perhaps we’re a little too far down the track to expect naked eye visibility. All we can do is to observe it and see!
Being such a southerly object, it will not be as well observed as novae in the northern hemisphere, but it’s in a great location, so have a go if you can! I’ll be out every clear night observing it when I can in the days to come, visually and possibly via DSLR.
I like to call this wide field (12 x 8 degrees) image, taken with a Canon 1100D (ISO 100, f2.0 100mm), nova interruptus. 🙂
The red arrow points to ASASSN-17gk (shown in inset), an 11th magnitude nova in Centaurus I observed on May 21. It also shows the trail left by a passenger airliner as it moved from top left to lower right during the one minute exposure, with tree-tops at bottom.
The signal to noise ratio wasn’t high enough to get a good value and error for the nova’s magnitude via DSLR photometry, so I didn’t submit an observation. The light curve at left shows observations made by others and the polynomial fit below highlights the rough shape of the light curve.
A request for observations by astronomers at the University of Wroclaw in Poland was announced by AAVSO on June 8.
The bright (magnitude 4.23 V) long period eclipsing binary HD 148703 (aka N Sco, HR 6143) is expected to undergo primary and secondary eclipses on June 11 and 14 each lasting around 20 hours.
The brightness and requested precision of 0.01 or better makes this an ideal candidate for wide field DSLR photometry.
I’ve taken pre-eclipse images but cloud prevented me from imaging the primary eclipse. I’ll take further images over the next few days, hoping to record the secondary eclipse.
