Welcome to MOST Hosts!

Programmed Observations

At the following link, you can find the MOST Hosts file (.csv), which contains a list of all the transients and their associated host candidates, which are programmed to be observed with DESI by the end of the survey. Please note that

• The volume of transients in our list has increased since the publication of the paper presenting the survey (Soumagnac et al. 2025), and now contains 1.7 times more transients than the volume of the sample presented in the paper.
• We adopted a conservative approach in selecting potential hosts, so each transient may have multiple candidate host galaxies associated with it (typically between 1 and 6).
• Specifically, there are 109,014 entries (postential host galaxiwas) in the MostHosts database for 66,465 different transients of which:
  • 38,484 are associated with 1 potential host
  • 13,857 are associated with 2 host candidates
  • 13,708 are associated with 3 host candidates
  • 399 are associated with 4 host candidates
  • 6 are associated with 5 host candidates
  • 11 are associated with 6 host candidates

Since each transient may have multiple candidate host galaxies, not all candidates have been observed yet. Therefore, the observed candidates for a given transients may not necessarily include its true host!

If you are interested in receiving a notification whenever new data is released, please leave your details in the following form.

Observed Candidates

You can access metadata files (.csv) and spectral archives (.tar.bz2) for the observed candidate host galaxies of the transients through the links below. The data in released on a rolling cadence on the 1st of each month.

Remark about the transient type: The transient type in the following files is listed under the column 'Obj. Type-Id', and it is represented using WISeREP code system. You can find the conversion on the WISeREP website.

Remark about the transient redshift:Note that the redshift column contains the redshift associated with the transient, when available. These redshifts originate from highly heterogeneous sources : in some cases, they are precise spectroscopic measurements; in others, they may come from informal observer notes in the ZTF Marshal. In many cases, the origin of the redshift is unclear. Importantly, we have redshift information for only about 30% of the transients.

The DESI redshift, when available, is recorded in the 'Spec-Remarks' column.

June 2025:

Statitics

• 44,071 hosts camdidates (40% of all the host candidates planned to be observed) have at least one high quality (zwarn=0) DESI redshift
• 39,982 transients (60 % of the total amount of transients) have at least one host observed by DESI
• 36,081 transients have 1 hosts observed by DESI with zwarn=0
• 3,716 transients have 2 hosts observed by DESI with zwarn=0
• 182 transients have 3 hosts observed by DESI with zwarn=0
• 3 transients have 4 hosts observed by DESI with zwarn=0
• 0 transients have 5 hosts observed by DESI with zwarn=0
• 0 transients have 6 hosts observed by DESI with zwarn=0

Data

• 0.csv
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• f.tar.bz2

August 2024:

Data

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• a.csv
• a.tar.bz2
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• b.tar.bz2
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• d.tar.bz2
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• f.csv
• f.tar.bz2