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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

63 results found.

  1. sb25061207: Mephisto optical upper limits
  2. GRB 250515A: 1.6m Mephisto optical detection
  3. EP250511a: Mephisto optical upper limits
  4. GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  5. GRB 250510A: SVOM possible detection of a burst
  6. GRB 250506A: Mephisto optical upper limits
  7. GRB 250419A: SVOM/ECLAIRs refined analysis
  8. GRB 250419A: Mephisto Multi-band Optical Detection
  9. EP250421a: Mephisto optical counterpart confirmation
  10. GRB 250419A: SVOM/VT optical continuous observations
  11. GRB 250419A: SVOM/C-GFT optical observations
  12. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  13. GRB 250419A: SVOM detection of a soft burst
  14. EP250404a: Mephisto multi-band optical detection
  15. GRB 250403A: 1.6m Mephisto multi-band optical detection
  16. GRB 250328A: 1.6m Mephisto optical observations
  17. GRB 250329B: SVOM/C-GFT optical upper limit
  18. GRB 250329B: SVOM/VT optical upper limit
  19. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  20. GRB 250329B: SVOM detection of a faint transient
  21. GRB 250329A: SVOM/VT optical counterpart confirmation
  22. GRB 250329A: SVOM detection of a burst
  23. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  24. GRB 250327B: 1.6m Mephisto optical observations
  25. EP250308a: 1.6m Mephisto optical upper limits
  26. EP250226a/GRB 250226A: 1.6m Mephisto observations
  27. EP250223a: 1.6m Mephisto and 50cm array observations
  28. GRB 250221A: 1.6m Mephisto optical detection
  29. EP250220a: 1.6m Mephisto observations
  30. GRB 250219A: 1.6m Mephisto optical upper limits
  31. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  32. GRB 250215A / EP250215a: SVOM/VT optical candidate comfirmation
  33. EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
  34. GRB 250109A / EP250109a: Mephisto optical upper limits
  35. EP250108a: Mephisto detection
  36. GRB 250103A: 1.6m Mephisto optical observations
  37. GRB 250101A: 1.6m Mephisto multi-band optical followup
  38. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
  39. EP241217a: 1.6m Mephisto multi-band optical observations
  40. GRB 241217a/EP241217B: 1.6m Mephisto optical upper limits
  41. EP241201a: 1.6m Mephisto Optical Upper Limits
  42. EP241126a: 1.6m Mephisto Optical Upper Limits
  43. EP trigger ID 01709122294: 1.6m Mephisto multi-band optical observations
  44. GRB 241112B: Mephisto further optical observations
  45. GRB 241115A: Mephisto upper limits
  46. GRB 241113B: Mephisto upper limits
  47. GRB 241113A: 1.6m Mephisto and 50cm array optical upper limits
  48. GRB 241112B: Optical afterglow detection confirmation in revisiting the Mephisto data
  49. GRB 241112B: Mephisto optical upper limits
  50. EP241021a: Optical rebrightening observations with Mephisto
  51. GRB 241030A: Multiband optical detection with Mephisto
  52. GRB 241029A: Mephisto observations
  53. EP241021a: EP-FXT follow-up observation update
  54. EP241021a: EP detection of a fast X-ray transient
  55. GRB 241018A/sb24101802: Mephisto optical upper limit
  56. GRB 241017A/sb24101702: Mephisto optical upper limit
  57. EP240913a/GRB 240913C: 1.6m Mephisto observations
  58. EP240918a: 1.6m Mephisto multi-band Optical Upper Limit
  59. GRB 240828B: Mephisto optical upper limit
  60. GRB 240825A: 1.6m Mephisto multi-band detection
  61. GRB 240811A: Upper limits with Mephisto
  62. GRB 240805B: Optical detection with 1.6m Mephisto
  63. LIGO/Virgo/KAGRA S240422ed: Observations with 1.6m Mephisto

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