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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"

905 results found.

  1. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  2. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  3. EP251221a: PRIME upper limit
  4. GRB 251222A / EP251222b: GECAM-B observation
  5. EP251222a: refined analysis of the EP-WXT and EP-FXT observations
  6. EP251222b/GRB 251222A: refined analysis of the EP-WXT and EP-FXT observations
  7. Konus-Wind detection of GRB 251222A / EP251222b
  8. EP251222b/GRB 251222A: Einstein Probe detection of an X-ray transient
  9. EP251222a: Einstein Probe detection of an X-ray transient
  10. The EP-WXT trigger 01709250397 is likely a flaring star
  11. EP251220a: VLT/FORS2 spectroscopic redshift z = 2.375
  12. EP251221a: Einstein Probe detection of a fast X-ray transient
  13. EP251220a: EP-FXT follow-up observation
  14. EP251220a: EP detection of a fast X-ray transient
  15. EP251214a: Optical upper limit with Kinder observations
  16. GRB 251202A: radio detection with the VLA
  17. EP251214b : Einstein Probe detection of a fast X-ray transient
  18. EP251214b : Einstein Probe detection of a fast X-ray transient
  19. EP251214a: EP-FXT non-detection and upper limit
  20. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  21. EP251212a / GRB 251212A: AstroSat CZTI detection
  22. EP251212a: EP-FXT follow-up observation
  23. EP251212a: Einstein Probe detection of an X-ray transient
  24. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  25. The EP-WXT trigger 01709249380 is likely a flaring star
  26. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  27. GRB 251202A: SVOM/GRM observation
  28. GRB 251203C: EP-FXT follow-up observation
  29. GRB 251129A / EP251129a: SVOM/VT optical color bluer
  30. EP251202a / GRB 251202A: Insight-HXMT/HE detection
  31. EP251202a / GRB251202A: AstroSat CZTI detection
  32. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  33. GRB 251202A: Fermi GBM Observation
  34. GRB 251202A: GOTO optical afterglow detection
  35. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  36. GRB 251202A: Swift-XRT afterglow detection
  37. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  38. EP251202a/trigger 01709249064: Las Cumbres discovery of the optical counterpart
  39. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  40. EP251130a: Optical detections with Kinder observations
  41. EP251130A: Optical observation from 1.3m DFOT
  42. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  43. EP251130a: Swift-XRT counterpart detection
  44. EP251130a: Einstein Probe detection of an X-ray transient
  45. EP251129a/GRB 251129A: EP-FXT follow-up observations
  46. GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460
  47. GRB 251129A / EP251129a: SAO RAS optical observations
  48. The EP-WXT trigger 01709248941 is triggered by the known source Perseus Cluster
  49. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  50. EP251124b follow-up observation by EP-FXT
  51. EP251124b: EP-WXT detection of a fast X-ray transient
  52. EP251124a (EP-WXT trigger 01709248862) is triggered by the known source AWM 7
  53. EP251124a: Swift-XRT observations
  54. EP251124a: Optical upper limit with Kinder observations
  55. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  56. EP251124a: Einstein Probe detection of an X-ray transient
  57. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  58. The EP-WXT trigger 01709248783 is likely a flaring star
  59. EP251118A: 3.6m DOT optical afterglow detection
  60. GRB 251122A / EP251122a: EP-FXT counterpart detection
  61. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  62. GRB 251122A / EP251122a: WFST optical observations
  63. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  64. EP251122a: Einstein Probe detection of an X-ray transient
  65. EP251118a: Continued Optical Detection with Kinder observations
  66. The EP-WXT trigger 01709248635 is likely a flaring star
  67. EP251118A: 1.3m DFOT optical afterglow detection
  68. EP251118a / GRB 251118C: SAO RAS optical observations
  69. EP251118a: Optical detection with Kinder observations
  70. The EP-WXT trigger 01709248403 is likely a flaring star
  71. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  72. The EP-WXT trigger 01709248388 is likely a flaring star
  73. EP251118a: preliminary result of EP-FXT follow-up observation
  74. EP251118a: NOT candidate optical counterpart
  75. EP251118a: Einstein Probe detected of a fast X-ray transient
  76. LIGO/Virgo/KAGRA S251112cm: EP-FXT follow-up observations
  77. GRB 251116B: EP-FXT follow-up observation
  78. The EP-WXT trigger 01709248221 is likely a flaring star
  79. GRB 251111A: Swift-XRT observations
  80. GRB 251111A: EP-FXT counterpart detection
  81. The EP-WXT trigger 01709248051 is likely a flaring star
  82. EP251102a: update of EP-FXT follow-up observation
  83. EP251102a: Einstein Probe detection of a fast X-ray transient
  84. EP251102a (WXT 11900459650): LCO observations confirm COLIBRÍ candidate
  85. GRB 251026A/EP251026a: EP-FXT follow-up observation
  86. The EP-WXT trigger 01709247588 is likely a flaring star
  87. The EP-WXT trigger 01709247525 is not a real source
  88. GRB 251026A/EP251026a: Einstein Probe detection of a fast X-ray transient
  89. EP251023b/GRB 251023B : Einstein Probe detection of a fast X-ray transient
  90. GRB 251023B: Glowbug gamma-ray detection
  91. EP251023a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at Teide Observatory
  92. EP#01709247298: Swift-XRT counterpart detection
  93. EP251023a: Einstein Probe detection of an X-ray transient
  94. EP/WXT 01709247295: GOTO optical afterglow candidate.
  95. EP251021b: BOOTES-7 optical upper limit
  96. EP251021b: Einstein Probe detection of a fast X-ray transient
  97. GRB 251013C: ULL-ASTRO-MASTER detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
  98. GRB 251013C: EP-FXT counterpart detection
  99. GRB 251006B: Fermi GBM Observation
  100. GRB 251006B/EP251006a: EP-FXT afterglow detection

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