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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"

92 results found.

  1. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  2. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  3. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  4. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  5. GRB 251111A: SVOM/ECLAIRs refined analysis
  6. GRB 251111A: SVOM/VT optical observations with X-band data
  7. GRB 251111A: EP-FXT counterpart detection
  8. GRB 251111A: SVOM/VT optical observations with VHF data
  9. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  10. GRB 251111A: SVOM detection of a soft burst
  11. GRB 250924A: 1.6m Mephisto optical upper limits
  12. The EP-WXT trigger EP250908a/01709240652 is not a real source
  13. EP250905b: EP-FXT follow-up observation
  14. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  15. EP250905b: EP-WXT detection of a fast X-ray transient
  16. EP250905a: Einstein Probe detection of an X-ray transient
  17. EP detected a brightening of LMXB 1ES 1735-26.9
  18. EP250901a: Mephisto optical upper limits
  19. GRB 250713A: Mephisto optical upper limits
  20. GRB 250704A: SVOM/ECLAIRs refined analysis
  21. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  22. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  23. GRB 250704A: SVOM/VT optical observation
  24. EP250704a / GRB 250704B: SVOM/VT optical blue counterpart
  25. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  26. EP250704a: Einstein Probe detection of an X-ray transient
  27. GRB 250704A: SVOM detection of a burst
  28. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  29. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  30. sb25061207: Mephisto optical upper limits
  31. GRB 250515A: 1.6m Mephisto optical detection
  32. EP250511a: Mephisto optical upper limits
  33. GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  34. GRB 250510A: SVOM possible detection of a burst
  35. GRB 250506A: Mephisto optical upper limits
  36. GRB 250419A: SVOM/ECLAIRs refined analysis
  37. GRB 250419A: Mephisto Multi-band Optical Detection
  38. EP250421a: Mephisto optical counterpart confirmation
  39. GRB 250419A: SVOM/VT optical continuous observations
  40. GRB 250419A: SVOM/C-GFT optical observations
  41. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  42. GRB 250419A: SVOM detection of a soft burst
  43. EP250404a: Mephisto multi-band optical detection
  44. GRB 250403A: 1.6m Mephisto multi-band optical detection
  45. GRB 250328A: 1.6m Mephisto optical observations
  46. GRB 250329B: SVOM/C-GFT optical upper limit
  47. GRB 250329B: SVOM/VT optical upper limit
  48. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  49. GRB 250329B: SVOM detection of a faint transient
  50. GRB 250329A: SVOM/VT optical counterpart confirmation
  51. GRB 250329A: SVOM detection of a burst
  52. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  53. GRB 250327B: 1.6m Mephisto optical observations
  54. EP250308a: 1.6m Mephisto optical upper limits
  55. EP250226a/GRB 250226A: 1.6m Mephisto observations
  56. EP250223a: 1.6m Mephisto and 50cm array observations
  57. GRB 250221A: 1.6m Mephisto optical detection
  58. EP250220a: 1.6m Mephisto observations
  59. GRB 250219A: 1.6m Mephisto optical upper limits
  60. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  61. GRB 250215A / EP250215a: SVOM/VT optical candidate comfirmation
  62. EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
  63. GRB 250109A / EP250109a: Mephisto optical upper limits
  64. EP250108a: Mephisto detection
  65. GRB 250103A: 1.6m Mephisto optical observations
  66. GRB 250101A: 1.6m Mephisto multi-band optical followup
  67. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
  68. EP241217a: 1.6m Mephisto multi-band optical observations
  69. GRB 241217a/EP241217B: 1.6m Mephisto optical upper limits
  70. EP241201a: 1.6m Mephisto Optical Upper Limits
  71. EP241126a: 1.6m Mephisto Optical Upper Limits
  72. EP trigger ID 01709122294: 1.6m Mephisto multi-band optical observations
  73. GRB 241112B: Mephisto further optical observations
  74. GRB 241115A: Mephisto upper limits
  75. GRB 241113B: Mephisto upper limits
  76. GRB 241113A: 1.6m Mephisto and 50cm array optical upper limits
  77. GRB 241112B: Optical afterglow detection confirmation in revisiting the Mephisto data
  78. GRB 241112B: Mephisto optical upper limits
  79. EP241021a: Optical rebrightening observations with Mephisto
  80. GRB 241030A: Multiband optical detection with Mephisto
  81. GRB 241029A: Mephisto observations
  82. EP241021a: EP-FXT follow-up observation update
  83. EP241021a: EP detection of a fast X-ray transient
  84. GRB 241018A/sb24101802: Mephisto optical upper limit
  85. GRB 241017A/sb24101702: Mephisto optical upper limit
  86. EP240913a/GRB 240913C: 1.6m Mephisto observations
  87. EP240918a: 1.6m Mephisto multi-band Optical Upper Limit
  88. GRB 240828B: Mephisto optical upper limit
  89. GRB 240825A: 1.6m Mephisto multi-band detection
  90. GRB 240811A: Upper limits with Mephisto
  91. GRB 240805B: Optical detection with 1.6m Mephisto
  92. LIGO/Virgo/KAGRA S240422ed: Observations with 1.6m Mephisto

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