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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"

89 results found.

  1. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  2. GRB 251111A: SVOM/ECLAIRs refined analysis
  3. GRB 251111A: SVOM/VT optical observations with X-band data
  4. GRB 251111A: EP-FXT counterpart detection
  5. GRB 251111A: SVOM/VT optical observations with VHF data
  6. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  7. GRB 251111A: SVOM detection of a soft burst
  8. GRB 250924A: 1.6m Mephisto optical upper limits
  9. The EP-WXT trigger EP250908a/01709240652 is not a real source
  10. EP250905b: EP-FXT follow-up observation
  11. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  12. EP250905b: EP-WXT detection of a fast X-ray transient
  13. EP250905a: Einstein Probe detection of an X-ray transient
  14. EP detected a brightening of LMXB 1ES 1735-26.9
  15. EP250901a: Mephisto optical upper limits
  16. GRB 250713A: Mephisto optical upper limits
  17. GRB 250704A: SVOM/ECLAIRs refined analysis
  18. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  19. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  20. GRB 250704A: SVOM/VT optical observation
  21. EP250704a / GRB 250704B: SVOM/VT optical blue counterpart
  22. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  23. EP250704a: Einstein Probe detection of an X-ray transient
  24. GRB 250704A: SVOM detection of a burst
  25. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  26. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  27. sb25061207: Mephisto optical upper limits
  28. GRB 250515A: 1.6m Mephisto optical detection
  29. EP250511a: Mephisto optical upper limits
  30. GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  31. GRB 250510A: SVOM possible detection of a burst
  32. GRB 250506A: Mephisto optical upper limits
  33. GRB 250419A: SVOM/ECLAIRs refined analysis
  34. GRB 250419A: Mephisto Multi-band Optical Detection
  35. EP250421a: Mephisto optical counterpart confirmation
  36. GRB 250419A: SVOM/VT optical continuous observations
  37. GRB 250419A: SVOM/C-GFT optical observations
  38. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  39. GRB 250419A: SVOM detection of a soft burst
  40. EP250404a: Mephisto multi-band optical detection
  41. GRB 250403A: 1.6m Mephisto multi-band optical detection
  42. GRB 250328A: 1.6m Mephisto optical observations
  43. GRB 250329B: SVOM/C-GFT optical upper limit
  44. GRB 250329B: SVOM/VT optical upper limit
  45. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  46. GRB 250329B: SVOM detection of a faint transient
  47. GRB 250329A: SVOM/VT optical counterpart confirmation
  48. GRB 250329A: SVOM detection of a burst
  49. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  50. GRB 250327B: 1.6m Mephisto optical observations
  51. EP250308a: 1.6m Mephisto optical upper limits
  52. EP250226a/GRB 250226A: 1.6m Mephisto observations
  53. EP250223a: 1.6m Mephisto and 50cm array observations
  54. GRB 250221A: 1.6m Mephisto optical detection
  55. EP250220a: 1.6m Mephisto observations
  56. GRB 250219A: 1.6m Mephisto optical upper limits
  57. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  58. GRB 250215A / EP250215a: SVOM/VT optical candidate comfirmation
  59. EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
  60. GRB 250109A / EP250109a: Mephisto optical upper limits
  61. EP250108a: Mephisto detection
  62. GRB 250103A: 1.6m Mephisto optical observations
  63. GRB 250101A: 1.6m Mephisto multi-band optical followup
  64. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
  65. EP241217a: 1.6m Mephisto multi-band optical observations
  66. GRB 241217a/EP241217B: 1.6m Mephisto optical upper limits
  67. EP241201a: 1.6m Mephisto Optical Upper Limits
  68. EP241126a: 1.6m Mephisto Optical Upper Limits
  69. EP trigger ID 01709122294: 1.6m Mephisto multi-band optical observations
  70. GRB 241112B: Mephisto further optical observations
  71. GRB 241115A: Mephisto upper limits
  72. GRB 241113B: Mephisto upper limits
  73. GRB 241113A: 1.6m Mephisto and 50cm array optical upper limits
  74. GRB 241112B: Optical afterglow detection confirmation in revisiting the Mephisto data
  75. GRB 241112B: Mephisto optical upper limits
  76. EP241021a: Optical rebrightening observations with Mephisto
  77. GRB 241030A: Multiband optical detection with Mephisto
  78. GRB 241029A: Mephisto observations
  79. EP241021a: EP-FXT follow-up observation update
  80. EP241021a: EP detection of a fast X-ray transient
  81. GRB 241018A/sb24101802: Mephisto optical upper limit
  82. GRB 241017A/sb24101702: Mephisto optical upper limit
  83. EP240913a/GRB 240913C: 1.6m Mephisto observations
  84. EP240918a: 1.6m Mephisto multi-band Optical Upper Limit
  85. GRB 240828B: Mephisto optical upper limit
  86. GRB 240825A: 1.6m Mephisto multi-band detection
  87. GRB 240811A: Upper limits with Mephisto
  88. GRB 240805B: Optical detection with 1.6m Mephisto
  89. LIGO/Virgo/KAGRA S240422ed: Observations with 1.6m Mephisto

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