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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"

2993 results found.

  1. GRB 251122A/EP251122a: CrAO ZTSh optical observations
  2. EP251202a / GRB 251202A: LCO r- and i-band optical detection
  3. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  4. GRB 251202A: Swift-XRT afterglow detection
  5. EP251129a/GRB 251129A: NOWT Detection
  6. EP251130a: SVOM/VT optical observation
  7. EP251202a / GRB 251202A: NOT spectroscopic redshift z = 2.785
  8. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  9. EP251202a/trigger 01709249064: Las Cumbres discovery of the optical counterpart
  10. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  11. EP251130a: Optical detections with Kinder observations
  12. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
  13. EP251130A: Optical observation from 1.3m DFOT
  14. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  15. EP251130a: Swift-XRT counterpart detection
  16. EP251130a: Global MASTER-Net observations report
  17. EP251130a: COLIBRÍ optical counterpart candidate
  18. EP251130a: Einstein Probe detection of an X-ray transient
  19. EP251129a/GRB 251129A: EP-FXT follow-up observations
  20. GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460
  21. GRB 251129A / EP251129a: OSN and CAHA optical follow-up
  22. GRB 251129A: Swift-XRT afterglow detection
  23. The EP-WXT trigger 01709248941 is triggered by the known source Perseus Cluster
  24. GRB 251129A / EP251129a: SVOM/VT optical fading
  25. EP251129a: Global MASTER-Net observations report
  26. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  27. EP251124a: Pan-STARRS ri-band imaging and photometry
  28. EP251124b follow-up observation by EP-FXT
  29. EP251124b: NOT r- and z-band optical upper limits
  30. EP251124b: Global MASTER-Net observations report
  31. EP251124b: EP-WXT detection of a fast X-ray transient
  32. EP251124a: Xinglong GWAC-F60A optical observation
  33. EP251124a (EP-WXT trigger 01709248862) is triggered by the known source AWM 7
  34. EP251124a: NOT r- and z-band optical upper limits
  35. EP251124a: Global MASTER-Net observations report
  36. EP251124a: Swift-XRT observations
  37. EP251124a: Optical upper limit with Kinder observations
  38. EP251118A: 6 GHz VLA Detection
  39. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  40. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  41. EP251124a: GROWTH-India Telescope optical upper limits
  42. EP251124a: Einstein Probe detection of an X-ray transient
  43. GRB 251122A/EP251122a: FTW optical and NIR observations
  44. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  45. The EP-WXT trigger 01709248783 is likely a flaring star
  46. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  47. GRB 251122A / EP251122a: EP-FXT counterpart detection
  48. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  49. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  50. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  51. GRB 251122A / EP251122a: LCO optical upper limits
  52. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  53. EP251122a: Global MASTER-Net observations report
  54. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  55. GRB 251122A / EP251122a: SVOM detection of a long burst
  56. EP251122a: Einstein Probe detection of an X-ray transient
  57. EP251118a: Continued Optical Detection with Kinder observations
  58. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  59. EP251118a: Xinglong-2.16m optical observation
  60. The EP-WXT trigger 01709248635 is likely a flaring star
  61. EP251118a: Optical detection with Kinder observations
  62. EP-WXT trigger 01709248403: confirmation of a stellar flare by SVOM/VT
  63. EP251118a / GRB 251118C: SVOM/VT optical observation
  64. The EP-WXT trigger 01709248403 is likely a flaring star
  65. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  66. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  67. Konus-Wind detection of GRB 251118C (EP251118a)
  68. The EP-WXT trigger 01709248388 is likely a flaring star
  69. EP251118a: VLT near-infrared observation
  70. EP251118a: GOTO optical afterglow detection
  71. EP251118a: Global MASTER-Net observations report
  72. EP251118a: preliminary result of EP-FXT follow-up observation
  73. EP251118a: NOT candidate optical counterpart
  74. EP251118a: Einstein Probe detected of a fast X-ray transient
  75. GRB 251116B: SVOM/VT optical upper limit
  76. EP251023a: Assy AZT-20 optical observations
  77. EP251023a: UAFO and AbAO optical observations
  78. LIGO/Virgo/KAGRA S251112cm: EP-FXT follow-up observations
  79. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  80. GRB 251116B: EP-FXT follow-up observation
  81. Konus-Wind detection of GRB 251108C
  82. Konus-Wind detection of GRB 251103A
  83. The EP-WXT trigger 01709248221 is likely a flaring star
  84. GRB 251111A: SVOM/VT optical observations with X-band data
  85. GRB 251111A: Swift-XRT observations
  86. GRB 251111A: EP-FXT counterpart detection
  87. GRB 251013C: Chandra X-ray observations and jet break detection
  88. The EP-WXT trigger 01709248051 is likely a flaring star
  89. EP251102a: Xinglong 2.16-m clear-band observations of the optical counterpart
  90. EP251102a: update of EP-FXT follow-up observation
  91. EP251102a: NIR observations with WINTER
  92. EP251102a: Einstein Probe detection of a fast X-ray transient
  93. EP251102a (WXT 11900459650): LCO observations confirm COLIBRÍ candidate
  94. EP251102.890: COLIBRÍ optical counterpart candidate
  95. Konus-Wind detection of GRB 251028A
  96. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  97. GRB 251026A/EP251026a: EP-FXT follow-up observation
  98. The EP-WXT trigger 01709247588 is likely a flaring star
  99. The EP-WXT trigger 01709247525 is not a real source
  100. GRB 251023B: Swift-UVOT Upper Limits

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