Supernovae Type Ia

About Supernovae Type Ia (SN Ia)

Supernovae Ia are created when a white dwarf's mass exceeds the Chandrasekhar limit of 1.4 times the mass of the Sun. This results in a runaway nuclear explosion, in which the white dwarf is destroyed. These appear observationally as new sources in the sky ("astronomical transients"), brighten for 10-20 days, and fade over a period of weeks to months. Since observing these objects requires relatively quick initial follow-ups, combined with repeated monitoring over a long period of time, the instrumentation we have available to us is well-suited to observing these objects.

Observing Campaign 2023

Although we have building our experience on these sources for several years, in 2023 we kicked off a larger scale campaign to systematically gather data on the early light curves of SN Ia. We used the Transient Name Server (daily digest) to select sources that were a) bright, b) visible in Aladin preview images (shown below), c) clearly associated with a galaxy, d) reasonably well-separated from the core of that galaxy, and e) observable with appropriate instrumentation on the iTelescope network. We will be publishing a more complete analysis of these sources, but here we present a selection.

SN2023cyx

in B and I filters, from the 0.51-m T11 telescope, 15 min in each image. In this case, there was likely some source confusion between the galaxy and the supernovae.

Light curve data can be found here - raw data available upon request.

SN2023hrn

In the galaxy NGC3535. These R and B filter images were the 0.508-m T30 telescope, and are 15 minutes each.

Light curve data can be found here - raw data available upon request.

Unobserved "failed" Sources

Since we are targeting the early light curves of SN Ia, and we don't have access to a large telescope and spectrometer, we had to begin observing sources before they were positively identified as SN Ia - before they were even positively identified as SN, instead of just blips in the data from ZTF and Gaia. Here is a list of those sources which we observed a small number of times, but could not identify them as clear transients, and won't be doing any followup observations of:

SN2023cju SN2023ctf AT2023dec AT2023eny AT2023gbs SN2023jto AT2023kjs AT2023lyt AT2023npw AT2023oxv AT2023see

Note that since TNS does not change the name from "AT" to "SN" until someone positively identifies the source, the fact that these are mostly AT means no one else has followed up on them either. Also note that we actually have follow-up observations on a couple of these, to implement a template subtraction procedure and maybe isolate the target. The list of targets which we have some reasonable data for follows.

MCARG Website Data

Observing Champaign 2024

In 2024 we've been doing follow-up observations of a selection of the galaxies to design a subtraction routine that would isolate the SN sources from their host galaxies. The initial routine was based on the GROWTH202 Astronomy School at Caltech, and has been further developed for our specific use case. A few notes about this particular approach:

It's possible that a better approach is the one taken by the recent TESS SN Ia studies (), initially presented by () and implemented in the software package ISIS. We are currently evaluating this package as a comparison with our current method.
The current method depends on external software packages, specifically SWarp (https://www.astromatic.net/software), SExtractor (https://www.astromatic.net/software), and PSFex (https://www.astromatic.net/software). While not inherently a drawback, these packages are rather tricky to install, and are likely to get trickier as they don't seem to be under active development. A better long-term solution would be to find alternatives within vanilla AstroPy.

Nevertheless, our current analysis routine does work, and so we will present the current results here. Except where indicated, these sources were all positively classified as SN Ia.

SN2023ctn

In the galaxy 2MFGC 6730. These I and B filter images were the 0.508-m T72 telescope, and are 15 minutes each.

Light curve data can be found here - raw data available upon request.

AT2023dpj

These Red and Green filter images were the 0.508-m T30 telescope, and are 7.5 minutes each.

Light curve data can be found here - raw data available upon request.

SN2023hst

These Red and Blue filter images were the 0.431-m T21 telescope, and are 15 minutes each.

Light curve data can be found here - raw data available upon request.

AT2023koy

These R and U filter images were the 0.508-m T30 telescope, and are 10 minutes each. In this case comparison stars for the U filter were not easily found, so the absolute scale of the magnitudes is not known.

SN2023pnt

These R and B filter images were from both the 0.51-m T11 and 0.431-m T21 telescope, and are 10 minutes each. This source was eventually identified as SN IIP.

Light curve data can be found here - raw data available upon request.

AT2023sse

These R filter images were from the 0.431-m T21 telescope, and are 10 minutes each. In this case the background was just too much to see anything in the B filter.

Light curve data can be found here - raw data available upon request.

AT2023umf

These R and B filter images were from the 0.431-m T21 telescope, and are 10 minutes each. This source remains unclassified, and looking at the light curve appears to be a misidentification from the burst alert network.

AT2023yfh

These R and B filter images were from the 0.51-m T11 and 0.431-m T21 telescope and are 20 minutes each. This source was actually classified as SN II.

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