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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"

82 results found.

  1. GRB 250924A: 1.6m Mephisto optical upper limits
  2. The EP-WXT trigger EP250908a/01709240652 is not a real source
  3. EP250905b: EP-FXT follow-up observation
  4. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  5. EP250905b: EP-WXT detection of a fast X-ray transient
  6. EP250905a: Einstein Probe detection of an X-ray transient
  7. EP detected a brightening of LMXB 1ES 1735-26.9
  8. EP250901a: Mephisto optical upper limits
  9. GRB 250713A: Mephisto optical upper limits
  10. GRB 250704A: SVOM/ECLAIRs refined analysis
  11. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  12. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  13. GRB 250704A: SVOM/VT optical observation
  14. EP250704a / GRB 250704B: SVOM/VT optical blue counterpart
  15. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  16. EP250704a: Einstein Probe detection of an X-ray transient
  17. GRB 250704A: SVOM detection of a burst
  18. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  19. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  20. sb25061207: Mephisto optical upper limits
  21. GRB 250515A: 1.6m Mephisto optical detection
  22. EP250511a: Mephisto optical upper limits
  23. GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  24. GRB 250510A: SVOM possible detection of a burst
  25. GRB 250506A: Mephisto optical upper limits
  26. GRB 250419A: SVOM/ECLAIRs refined analysis
  27. GRB 250419A: Mephisto Multi-band Optical Detection
  28. EP250421a: Mephisto optical counterpart confirmation
  29. GRB 250419A: SVOM/VT optical continuous observations
  30. GRB 250419A: SVOM/C-GFT optical observations
  31. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  32. GRB 250419A: SVOM detection of a soft burst
  33. EP250404a: Mephisto multi-band optical detection
  34. GRB 250403A: 1.6m Mephisto multi-band optical detection
  35. GRB 250328A: 1.6m Mephisto optical observations
  36. GRB 250329B: SVOM/C-GFT optical upper limit
  37. GRB 250329B: SVOM/VT optical upper limit
  38. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  39. GRB 250329B: SVOM detection of a faint transient
  40. GRB 250329A: SVOM/VT optical counterpart confirmation
  41. GRB 250329A: SVOM detection of a burst
  42. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  43. GRB 250327B: 1.6m Mephisto optical observations
  44. EP250308a: 1.6m Mephisto optical upper limits
  45. EP250226a/GRB 250226A: 1.6m Mephisto observations
  46. EP250223a: 1.6m Mephisto and 50cm array observations
  47. GRB 250221A: 1.6m Mephisto optical detection
  48. EP250220a: 1.6m Mephisto observations
  49. GRB 250219A: 1.6m Mephisto optical upper limits
  50. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  51. GRB 250215A / EP250215a: SVOM/VT optical candidate comfirmation
  52. EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
  53. GRB 250109A / EP250109a: Mephisto optical upper limits
  54. EP250108a: Mephisto detection
  55. GRB 250103A: 1.6m Mephisto optical observations
  56. GRB 250101A: 1.6m Mephisto multi-band optical followup
  57. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
  58. EP241217a: 1.6m Mephisto multi-band optical observations
  59. GRB 241217a/EP241217B: 1.6m Mephisto optical upper limits
  60. EP241201a: 1.6m Mephisto Optical Upper Limits
  61. EP241126a: 1.6m Mephisto Optical Upper Limits
  62. EP trigger ID 01709122294: 1.6m Mephisto multi-band optical observations
  63. GRB 241112B: Mephisto further optical observations
  64. GRB 241115A: Mephisto upper limits
  65. GRB 241113B: Mephisto upper limits
  66. GRB 241113A: 1.6m Mephisto and 50cm array optical upper limits
  67. GRB 241112B: Optical afterglow detection confirmation in revisiting the Mephisto data
  68. GRB 241112B: Mephisto optical upper limits
  69. EP241021a: Optical rebrightening observations with Mephisto
  70. GRB 241030A: Multiband optical detection with Mephisto
  71. GRB 241029A: Mephisto observations
  72. EP241021a: EP-FXT follow-up observation update
  73. EP241021a: EP detection of a fast X-ray transient
  74. GRB 241018A/sb24101802: Mephisto optical upper limit
  75. GRB 241017A/sb24101702: Mephisto optical upper limit
  76. EP240913a/GRB 240913C: 1.6m Mephisto observations
  77. EP240918a: 1.6m Mephisto multi-band Optical Upper Limit
  78. GRB 240828B: Mephisto optical upper limit
  79. GRB 240825A: 1.6m Mephisto multi-band detection
  80. GRB 240811A: Upper limits with Mephisto
  81. GRB 240805B: Optical detection with 1.6m Mephisto
  82. LIGO/Virgo/KAGRA S240422ed: Observations with 1.6m Mephisto

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