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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"

1094 results found.

  1. EP251221a: Einstein Probe detection of a fast X-ray transient
  2. EP251220a: EP-FXT follow-up observation
  3. EP251220a: EP detection of a fast X-ray transient
  4. EP251214a: Optical upper limit with Kinder observations
  5. GRB 251202A: radio detection with the VLA
  6. EP251214b : Einstein Probe detection of a fast X-ray transient
  7. EP251214b : Einstein Probe detection of a fast X-ray transient
  8. EP251214a: EP-FXT non-detection and upper limit
  9. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  10. EP251212a / GRB 251212A: AstroSat CZTI detection
  11. EP251212a: EP-FXT follow-up observation
  12. EP251212a: Einstein Probe detection of an X-ray transient
  13. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  14. The EP-WXT trigger 01709249380 is likely a flaring star
  15. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  16. GRB 251202A: SVOM/GRM observation
  17. GRB 251203C: EP-FXT follow-up observation
  18. GRB 251129A / EP251129a: SVOM/VT optical color bluer
  19. EP251202a / GRB 251202A: Insight-HXMT/HE detection
  20. EP251202a / GRB251202A: AstroSat CZTI detection
  21. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  22. GRB 251202A: Fermi GBM Observation
  23. GRB 251202A: GOTO optical afterglow detection
  24. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  25. GRB 251202A: Swift-XRT afterglow detection
  26. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  27. EP251202a/trigger 01709249064: Las Cumbres discovery of the optical counterpart
  28. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  29. EP251130a: Optical detections with Kinder observations
  30. EP251130A: Optical observation from 1.3m DFOT
  31. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  32. EP251130a: Swift-XRT counterpart detection
  33. EP251130a: Einstein Probe detection of an X-ray transient
  34. EP251129a/GRB 251129A: EP-FXT follow-up observations
  35. GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460
  36. GRB 251129A / EP251129a: SAO RAS optical observations
  37. The EP-WXT trigger 01709248941 is triggered by the known source Perseus Cluster
  38. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  39. EP251124b follow-up observation by EP-FXT
  40. EP251124b: EP-WXT detection of a fast X-ray transient
  41. EP251124a (EP-WXT trigger 01709248862) is triggered by the known source AWM 7
  42. EP251124a: Swift-XRT observations
  43. EP251124a: Optical upper limit with Kinder observations
  44. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  45. EP251124a: Einstein Probe detection of an X-ray transient
  46. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  47. The EP-WXT trigger 01709248783 is likely a flaring star
  48. EP251118A: 3.6m DOT optical afterglow detection
  49. GRB 251122A / EP251122a: EP-FXT counterpart detection
  50. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  51. GRB 251122A / EP251122a: WFST optical observations
  52. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  53. EP251122a: Einstein Probe detection of an X-ray transient
  54. EP251118a: Continued Optical Detection with Kinder observations
  55. The EP-WXT trigger 01709248635 is likely a flaring star
  56. EP251118A: 1.3m DFOT optical afterglow detection
  57. EP251118a / GRB 251118C: SAO RAS optical observations
  58. EP251118a: Optical detection with Kinder observations
  59. The EP-WXT trigger 01709248403 is likely a flaring star
  60. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  61. The EP-WXT trigger 01709248388 is likely a flaring star
  62. EP251118a: preliminary result of EP-FXT follow-up observation
  63. EP251118a: NOT candidate optical counterpart
  64. EP251118a: Einstein Probe detected of a fast X-ray transient
  65. LIGO/Virgo/KAGRA S251112cm: EP-FXT follow-up observations
  66. GRB 251116B: EP-FXT follow-up observation
  67. The EP-WXT trigger 01709248221 is likely a flaring star
  68. GRB 251111A: Swift-XRT observations
  69. GRB 251111A: EP-FXT counterpart detection
  70. The EP-WXT trigger 01709248051 is likely a flaring star
  71. EP251102a: update of EP-FXT follow-up observation
  72. EP251102a: Einstein Probe detection of a fast X-ray transient
  73. EP251102a (WXT 11900459650): LCO observations confirm COLIBRÍ candidate
  74. GRB 251026A/EP251026a: EP-FXT follow-up observation
  75. The EP-WXT trigger 01709247588 is likely a flaring star
  76. The EP-WXT trigger 01709247525 is not a real source
  77. GRB 251026A/EP251026a: Einstein Probe detection of a fast X-ray transient
  78. EP251023b/GRB 251023B : Einstein Probe detection of a fast X-ray transient
  79. GRB 251023B: Glowbug gamma-ray detection
  80. EP251023a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at Teide Observatory
  81. EP#01709247298: Swift-XRT counterpart detection
  82. EP251023a: Einstein Probe detection of an X-ray transient
  83. EP/WXT 01709247295: GOTO optical afterglow candidate.
  84. EP251021b: BOOTES-7 optical upper limit
  85. EP251021b: Einstein Probe detection of a fast X-ray transient
  86. GRB 251013C: ULL-ASTRO-MASTER detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
  87. GRB 251013C: EP-FXT counterpart detection
  88. GRB 251006B: Fermi GBM Observation
  89. GRB 251006B/EP251006a: EP-FXT afterglow detection
  90. GRB 251006B/EP251006a: EP-FXT follow-up observation
  91. GRB 251006B/EP251006a: EP-WXT detection
  92. EP251003a: Einstein Probe detection of an X-ray transient
  93. EP250821a: iTelescope T-59 possible detection of the optical counterpart
  94. GRB 251002A: EP-FXT counterpart detection
  95. GRB 250925A/EP250925a: EP-WXT detection
  96. GRB 250919A: Glowbug gamma-ray detection
  97. GRB 250919A: Swift-XRT afterglow detection
  98. EP250919a: Einstein Probe detection of an X-ray transient
  99. The EP-WXT trigger 01709243841: Las Cumbres discovery of the optical counterpart
  100. EP250916a: EP-FXT follow-up observation

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