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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"

2962 results found.

  1. EP251124a: Xinglong GWAC-F60A optical observation
  2. EP251124a (EP-WXT trigger 01709248862) is triggered by the known source AWM 7
  3. EP251124a: NOT r- and z-band optical upper limits
  4. EP251124a: Global MASTER-Net observations report
  5. EP251124a: Swift-XRT observations
  6. EP251124a: Optical upper limit with Kinder observations
  7. EP251118A: 6 GHz VLA Detection
  8. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  9. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  10. EP251124a: GROWTH-India Telescope optical upper limits
  11. EP251124a: Einstein Probe detection of an X-ray transient
  12. GRB 251122A/EP251122a: FTW optical and NIR observations
  13. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  14. The EP-WXT trigger 01709248783 is likely a flaring star
  15. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  16. GRB 251122A / EP251122a: EP-FXT counterpart detection
  17. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  18. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  19. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  20. GRB 251122A / EP251122a: LCO optical upper limits
  21. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  22. EP251122a: Global MASTER-Net observations report
  23. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  24. GRB 251122A / EP251122a: SVOM detection of a long burst
  25. EP251122a: Einstein Probe detection of an X-ray transient
  26. EP251118a: Continued Optical Detection with Kinder observations
  27. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  28. EP251118a: Xinglong-2.16m optical observation
  29. The EP-WXT trigger 01709248635 is likely a flaring star
  30. EP251118a: Optical detection with Kinder observations
  31. EP-WXT trigger 01709248403: confirmation of a stellar flare by SVOM/VT
  32. EP251118a / GRB 251118C: SVOM/VT optical observation
  33. The EP-WXT trigger 01709248403 is likely a flaring star
  34. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  35. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  36. Konus-Wind detection of GRB 251118C (EP251118a)
  37. The EP-WXT trigger 01709248388 is likely a flaring star
  38. EP251118a: VLT near-infrared observation
  39. EP251118a: GOTO optical afterglow detection
  40. EP251118a: Global MASTER-Net observations report
  41. EP251118a: preliminary result of EP-FXT follow-up observation
  42. EP251118a: NOT candidate optical counterpart
  43. EP251118a: Einstein Probe detected of a fast X-ray transient
  44. GRB 251116B: SVOM/VT optical upper limit
  45. EP251023a: Assy AZT-20 optical observations
  46. EP251023a: UAFO and AbAO optical observations
  47. LIGO/Virgo/KAGRA S251112cm: EP-FXT follow-up observations
  48. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  49. GRB 251116B: EP-FXT follow-up observation
  50. Konus-Wind detection of GRB 251108C
  51. Konus-Wind detection of GRB 251103A
  52. The EP-WXT trigger 01709248221 is likely a flaring star
  53. GRB 251111A: SVOM/VT optical observations with X-band data
  54. GRB 251111A: Swift-XRT observations
  55. GRB 251111A: EP-FXT counterpart detection
  56. GRB 251013C: Chandra X-ray observations and jet break detection
  57. The EP-WXT trigger 01709248051 is likely a flaring star
  58. EP251102a: Xinglong 2.16-m clear-band observations of the optical counterpart
  59. EP251102a: update of EP-FXT follow-up observation
  60. EP251102a: NIR observations with WINTER
  61. EP251102a: Einstein Probe detection of a fast X-ray transient
  62. EP251102a (WXT 11900459650): LCO observations confirm COLIBRÍ candidate
  63. EP251102.890: COLIBRÍ optical counterpart candidate
  64. Konus-Wind detection of GRB 251028A
  65. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  66. GRB 251026A/EP251026a: EP-FXT follow-up observation
  67. The EP-WXT trigger 01709247588 is likely a flaring star
  68. The EP-WXT trigger 01709247525 is not a real source
  69. GRB 251023B: Swift-UVOT Upper Limits
  70. Konus-Wind detection of GRB 251022A
  71. EP251027.145: COLIBRÍ optical upper limits
  72. GRB 251026A/EP251026a: Einstein Probe detection of a fast X-ray transient
  73. Konus-Wind detection of GRB 251016A (short/hard)
  74. EP251023a: Mondy optical observations
  75. Konus-Wind detection of GRB 251016B
  76. EP251023a: MAO/AZT-22 optical observations
  77. EP251023b: Global MASTER-Net observations report
  78. EP251023b/GRB 251023B : Einstein Probe detection of a fast X-ray transient
  79. EP251023a: GROWTH-India Telescope optical observations
  80. GRB 251023B: Glowbug gamma-ray detection
  81. EP251023a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at Teide Observatory
  82. EP251023a: Global MASTER-Net observations report
  83. GRB 251023B / EP#01709247298: COLIBRÍ optical counterpart candidate
  84. EP#01709247298: Swift-XRT counterpart detection
  85. EP251023a: Keck/LRIS spectroscopic redshift z=2.232
  86. EP251021b/GRB 251021A: SVOM/VT optical candidate
  87. EP251023a: NOT optical counterpart detection
  88. EP251023a: GSP Optical Counterpart Detection
  89. EP251023a: Einstein Probe detection of an X-ray transient
  90. EP/WXT 01709247295: GOTO optical afterglow candidate.
  91. GRB 251021A/EP251021b: Fermi-GBM Sub-Threshold Detection
  92. EP251021b: BOOTES-7 optical upper limit
  93. EP251021b: Einstein Probe detection of a fast X-ray transient
  94. Konus-Wind detection of GRB 251007A
  95. GRB 251013C: EP-FXT counterpart detection
  96. GRB 250919A: TERI gamma-ray detection
  97. EP251006a: Global MASTER-Net observations report
  98. GRB 251006B: Fermi GBM Observation
  99. GRB 251006B/EP251006a: EP-FXT afterglow detection
  100. GRB 251006B: Insight-HXMT detection

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