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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"

3320 results found.

  1. EP251214b : Einstein Probe detection of a fast X-ray transient
  2. EP251214b : Einstein Probe detection of a fast X-ray transient
  3. EP251214b (EP trigger 01709250023): LCO optical limits
  4. EP251214a: KAIT optical upper limit
  5. EP251214a: EP-FXT non-detection and upper limit
  6. EP251214a: Global MASTER-Net observations report
  7. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  8. EP251212a: Global MASTER-Net observations report
  9. EP251212a: KAIT optical upper limit
  10. EP251212a: EP-FXT follow-up observation
  11. EP251212a: Einstein Probe detection of an X-ray transient
  12. EP251124a: Mondy optical upper limit
  13. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  14. EP-WXT trigger 01709249380: KAIT confirmation of a stellar flare
  15. EP-WXT trigger 01709249380: confirmation of a stellar flare by BOOTES-5
  16. The EP-WXT trigger 01709249380 is likely a flaring star
  17. Konus-Wind detection of GRB 251118A
  18. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  19. GRB 251202A: SVOM/GRM observation
  20. GRB 251203C: EP-FXT follow-up observation
  21. GRB 251129A/EP251129a : SVOM/ECLAIRs refined analysis
  22. EP251202a / GRB 251202A: Insight-HXMT/HE detection
  23. EP251130a: MAO/AZT-22 optical observations
  24. GRB 251202A / EP251202a: SVOM/VT optical observation
  25. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  26. GRB251129A/EP251129a: Swift UVOT detection
  27. GRB 251202A: Swift/UVOT Detection
  28. GRB 251122A/EP251122a: CrAO ZTSh optical observations
  29. EP251202a / GRB 251202A: LCO r- and i-band optical detection
  30. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  31. GRB 251202A: Swift-XRT afterglow detection
  32. EP251129a/GRB 251129A: NOWT Detection
  33. EP251130a: SVOM/VT optical observation
  34. EP251202a / GRB 251202A: NOT spectroscopic redshift z = 2.785
  35. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  36. EP251202a/trigger 01709249064: Las Cumbres discovery of the optical counterpart
  37. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  38. EP251130a: Optical detections with Kinder observations
  39. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
  40. EP251130A: Optical observation from 1.3m DFOT
  41. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  42. EP251130a: Swift-XRT counterpart detection
  43. EP251130a: Global MASTER-Net observations report
  44. EP251130a: COLIBRÍ optical counterpart candidate
  45. EP251130a: Einstein Probe detection of an X-ray transient
  46. EP251129a/GRB 251129A: EP-FXT follow-up observations
  47. GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460
  48. GRB 251129A / EP251129a: OSN and CAHA optical follow-up
  49. GRB 251129A: Swift-XRT afterglow detection
  50. The EP-WXT trigger 01709248941 is triggered by the known source Perseus Cluster
  51. GRB 251129A / EP251129a: SVOM/VT optical fading
  52. EP251129a: Global MASTER-Net observations report
  53. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  54. EP251124a: Pan-STARRS ri-band imaging and photometry
  55. EP251124b follow-up observation by EP-FXT
  56. EP251124b: NOT r- and z-band optical upper limits
  57. EP251124b: Global MASTER-Net observations report
  58. EP251124b: EP-WXT detection of a fast X-ray transient
  59. EP251124a: Xinglong GWAC-F60A optical observation
  60. EP251124a (EP-WXT trigger 01709248862) is triggered by the known source AWM 7
  61. EP251124a: NOT r- and z-band optical upper limits
  62. EP251124a: Global MASTER-Net observations report
  63. EP251124a: Swift-XRT observations
  64. EP251124a: Optical upper limit with Kinder observations
  65. EP251118A: 6 GHz VLA Detection
  66. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  67. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  68. EP251124a: GROWTH-India Telescope optical upper limits
  69. EP251124a: Einstein Probe detection of an X-ray transient
  70. GRB 251122A/EP251122a: FTW optical and NIR observations
  71. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  72. The EP-WXT trigger 01709248783 is likely a flaring star
  73. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  74. GRB 251122A / EP251122a: EP-FXT counterpart detection
  75. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  76. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  77. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  78. GRB 251122A / EP251122a: LCO optical upper limits
  79. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  80. EP251122a: Global MASTER-Net observations report
  81. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  82. GRB 251122A / EP251122a: SVOM detection of a long burst
  83. EP251122a: Einstein Probe detection of an X-ray transient
  84. EP251118a: Continued Optical Detection with Kinder observations
  85. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  86. EP251118a: Xinglong-2.16m optical observation
  87. The EP-WXT trigger 01709248635 is likely a flaring star
  88. EP251118a: Optical detection with Kinder observations
  89. EP-WXT trigger 01709248403: confirmation of a stellar flare by SVOM/VT
  90. EP251118a / GRB 251118C: SVOM/VT optical observation
  91. The EP-WXT trigger 01709248403 is likely a flaring star
  92. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  93. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  94. Konus-Wind detection of GRB 251118C (EP251118a)
  95. The EP-WXT trigger 01709248388 is likely a flaring star
  96. EP251118a: VLT near-infrared observation
  97. EP251118a: GOTO optical afterglow detection
  98. EP251118a: Global MASTER-Net observations report
  99. EP251118a: preliminary result of EP-FXT follow-up observation
  100. EP251118a: NOT candidate optical counterpart

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