GA pilot flying reported an near midair collision without a traffic alert from ATC.

Attributes
ACN	1758823
Time
Date	202008
Local Time Of Day	1201-1800
Place
Locale Reference	ZFW.ARTCC
State Reference	TX
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Baron 58/58TC
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Route In Use	Direct
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	Cruise
Person 1
Function	Captain Pilot Flying Single Pilot
Qualification	Flight Crew Instrument Flight Crew Commercial Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 168 Flight Crew Total 1168 Flight Crew Type 463
Events
Anomaly	ATC Issue All Types Conflict Airborne Conflict Conflict NMAC Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy
Miss Distance	Horizontal 200 Vertical 500

Narrative:

Near midair collision occurred in autopilot cruise at 9;000 ft. In VMC. I looked up to see traffic at approximately 11 o'clock approaching me head-on. I estimate the traffic was between 400 to 500 ft. Below my altitude and 200 to 300 ft. To my left. In the time it took to recognize the situation; the traffic had already passed behind me; and I did not see it again. I immediately advised ZFW; including color and type of aircraft. At first; the center controller did not see anyone else on radar; but after a moment said he could see a primary target with no transponder information right behind me. He did not inquire further; and my flight continued normally.

Original NASA ASRS Text

Title: GA pilot flying reported an NMAC without a traffic alert from ATC.

Narrative: NMAC occurred in autopilot cruise at 9;000 ft. in VMC. I looked up to see traffic at approximately 11 o'clock approaching me head-on. I estimate the traffic was between 400 to 500 ft. below my altitude and 200 to 300 ft. to my left. In the time it took to recognize the situation; the traffic had already passed behind me; and I did not see it again. I immediately advised ZFW; including color and type of aircraft. At first; the Center controller did not see anyone else on radar; but after a moment said he could see a primary target with no transponder information right behind me. He did not inquire further; and my flight continued normally.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.